Adaptive film grain synthesis

ABSTRACT

Systems and techniques are described herein for processing video data. For instance, a process can include obtaining video data including a picture. The process can also include determining a width of a film grain synthesis block of the picture based on at least one of a width and a height of the picture. The process can further include determining a height of the film grain synthesis block of the picture is one. The process may also include determining a block size of the film grain synthesis block based on the determined width and height. The process may further include selecting a grain block based on the determined block size.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.63/265,092, filed Dec. 7, 2021. This application also claims the benefitof U.S. Provisional Application No. 63/320,095, filed Mar. 15, 2022.This application also claims the benefit of U.S. Provisional ApplicationNo. 63/331,765, filed Apr. 15, 2022. The disclosure of the foregoingprovisional applications is hereby incorporated by reference, in itsentirety and for all purposes.

TECHNICAL FIELD

This application is generally related to video processing. For example,aspects of the application relate to improving video coding techniques(e.g., encoding and/or decoding video) with respect to adaptive filmgrain synthesis.

BACKGROUND

Digital video capabilities can be incorporated into a wide range ofdevices, including digital televisions, digital direct broadcastsystems, wireless broadcast systems, personal digital assistants (PDAs),laptop or desktop computers, tablet computers, e-book readers, digitalcameras, digital recording devices, digital media players, video gamingdevices, video game consoles, cellular or satellite radio telephones,so-called “smart phones,” video teleconferencing devices, videostreaming devices, and the like. Such devices allow video data to beprocessed and output for consumption. Digital video data includes largeamounts of data to meet the demands of consumers and video providers.For example, consumers of video data desire video of the utmost quality,with high fidelity, resolutions, frame rates, and the like. As a result,the large amount of video data that is required to meet these demandsplaces a burden on communication networks and devices that process andstore the video data.

Digital video devices can implement video coding techniques to compressvideo data. Video coding is performed according to one or more videocoding standards or formats. For example, video coding standards orformats include versatile video coding (VVC), high-efficiency videocoding (HEVC), advanced video coding (AVC), MPEG-2 Part 2 coding (MPEGstands for moving picture experts group), Essential Video Coding (EVC),among others, as well as proprietary video coder-decoder(codecs)/formats such as AOMedia Video 1 (AV1) that was developed by theAlliance for Open Media. Video coding generally utilizes predictionmethods (e.g., inter prediction, intra prediction, or the like) thattake advantage of redundancy present in video images or sequences. Agoal of video coding techniques is to compress video data into a formthat uses a lower bit rate, while avoiding or minimizing degradations tovideo quality. With ever-evolving video services becoming available,coding techniques with better coding efficiency are needed.

SUMMARY

Systems and techniques are described herein for processing video data.According to at least one example, a method of processing video isprovided, including: obtaining a picture; and determining at least oneof a width and a height of a film grain synthesis block of the picturebased on at least one of a width and a height of the picture.

According to at least one other example, an apparatus is provided forprocessing video data, including at least one memory and at least oneprocessor (e.g., implemented in circuitry) coupled to the at least onememory. The at least one processor is configured to: obtain video dataincluding a picture; determine a width of a film grain synthesis blockof the picture based on at least one of a width and a height of thepicture; determine a height of the film grain synthesis block of thepicture is one; determine a block size of the film grain synthesis blockbased on the determined width and height; and select a grain block basedon the determined block size.

As another example, a method is provided for processing video data. Themethod includes: obtaining video data including a picture; determining awidth of a film grain synthesis block of the picture based on at leastone of a width and a height of the picture; determining a height of thefilm grain synthesis block of the picture is one; determining a blocksize of the film grain synthesis block based on the determined width andheight; and selecting a grain block based on the determined block size.

In another example, a non-transitory computer-readable medium havingstored thereon instructions that, when executed by at least one or moreprocessors, cause the at least one or more processors to: obtain videodata including a picture. The instructions further cause the at leastone or more processors to determine a width of a film grain synthesisblock of the picture based on at least one of a width and a height ofthe picture; determine a height of the film grain synthesis block of thepicture is one; determine a block size of the film grain synthesis blockbased on the determined width and height; and select a grain block basedon the determined block size.

As another example, an apparatus is provided for processing video data.The apparatus includes: means for obtaining video data including apicture; means for determining a width of a film grain synthesis blockof the picture based on at least one of a width and a height of thepicture; means for determining a height of the film grain synthesisblock of the picture is one; means for determining a block size of thefilm grain synthesis block based on the determined width and height; andmeans for selecting a grain block based on the determined block size.

In some aspects, any of the apparatuses or devices described above is,is part of, and/or includes a mobile device (e.g., a mobile telephone orso-called “smart phone” or other mobile device), a wearable device, anextended reality device (e.g., a virtual reality (VR) device, anaugmented reality (AR) device, or a mixed reality (MR) device), acamera, a personal computer, a laptop computer, a server computer, avehicle or a computing device or component of a vehicle, a roboticsdevice or system, a television, or other device. In some aspects, theapparatuses or devices include a camera or multiple cameras forcapturing one or more pictures, images, or frames. In some aspects, theapparatuses or devices include a display for displaying one or moreimages, notifications, and/or other displayable data. In some aspects,the apparatuses or devices can include one or more sensors (e.g., one ormore inertial measurement units (IMUs), such as one or more gyrometers,one or more accelerometers, any combination thereof, and/or othersensor.

This summary is not intended to identify key or essential features ofthe claimed subject matter, nor is it intended to be used in isolationto determine the scope of the claimed subject matter. The subject mattershould be understood by reference to appropriate portions of the entirespecification of this patent, any or all drawings, and each claim.

The foregoing, together with other features and embodiments, will becomemore apparent upon referring to the following specification, claims, andaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative examples of the present application are described in detailbelow with reference to the following figures:

FIG. 1 is a block diagram illustrating an example of an encoding deviceand a decoding device, in accordance with some aspects of thedisclosure;

FIG. 2 is a block diagram illustrating a film grain synthesis workflowfor Society of Motion Picture and Television Engineers (SMPTE)Registered Disclosure Document (RDD) 5, in accordance with some aspectsof the disclosure;

FIG. 3 is a block diagram illustrating an example of a line buffer forfilm grain synthesis, in accordance with some aspects of the disclosure;

FIGS. 4A-4B are a flow diagram illustrating a process for film grainsynthesis, in accordance with aspects of the present disclosure;

FIG. 5 is a flow diagram illustrating process for processing video data,in accordance with aspects of the present disclosure;

FIG. 6 is a block diagram illustrating an example video encoding device,in accordance with some aspects of the disclosure; and

FIG. 7 is a block diagram illustrating an example video decoding device,in accordance with some aspects of the disclosure.

DETAILED DESCRIPTION

Certain aspects and embodiments of this disclosure are provided below.Some of these aspects and embodiments may be applied independently andsome of them may be applied in combination as would be apparent to thoseof skill in the art. In the following description, for the purposes ofexplanation, specific details are set forth in order to provide athorough understanding of embodiments of the application. However, itwill be apparent that various embodiments may be practiced without thesespecific details. The figures and description are not intended to berestrictive.

The ensuing description provides exemplary embodiments only, and is notintended to limit the scope, applicability, or configuration of thedisclosure. Rather, the ensuing description of the exemplary embodimentswill provide those skilled in the art with an enabling description forimplementing an exemplary embodiment. It should be understood thatvarious changes may be made in the function and arrangement of elementswithout departing from the spirit and scope of the application as setforth in the appended claims.

Film grain generally refers to random optical texture that can appear inprocessed photographic films. As film grain can be expensive to encode,film grain can be characterized and removed by filtering duringencoding. The characterized film grain may then be added back duringdecoding. The film grain for a picture of a video may be characterizedbased on an average luma value of a portion (e.g., a current block) ofthe picture.

In many cases, the average luma value of the portion is determined byreading at least a portion of each line of the portion of the pictureinto a line buffer. While line buffers are relatively common in imageand video processing circuits, line buffers can occupy a relativelylarge amount of on-chip area and thus can be relatively expensive toimplement.

To reduce use of line buffers, in some cases, an average luma value ofthe portion may be determined by reading a single line of the portion ofthe picture into a buffer and determining an average luma value of thesingle line. In some cases, as an amount of data associated with asingle line of the portion of the picture is relatively small, the dataassociated with the single line of the portion of the picture may bestored in any accessible memory and does not need to be stored in a linebuffer. In some cases, average luma values may be determined for eachline of the portion of the picture, and these average luma values may beaveraged to generate the average luma value (e.g., overall average lumavalue) of the portion.

Video coding devices implement video compression techniques to encodeand decode video data efficiently. Video compression techniques mayinclude applying different prediction modes, including spatialprediction (e.g., intra-frame prediction or intra-prediction), temporalprediction (e.g., inter-frame prediction or inter-prediction),inter-layer prediction (across different layers of video data), and/orother prediction techniques to reduce or remove redundancy inherent invideo sequences. A video encoder can partition each picture of anoriginal video sequence into rectangular regions referred to as videoblocks or coding units (described in greater detail below). These videoblocks may be encoded using a particular prediction mode.

Video blocks may be divided in one or more ways into one or more groupsof smaller blocks. Blocks can include coding tree blocks, predictionblocks, transform blocks, or other suitable blocks. References generallyto a “block,” unless otherwise specified, may refer to such video blocks(e.g., coding tree blocks, coding blocks, prediction blocks, transformblocks, or other appropriate blocks or sub-blocks, as would beunderstood by one of ordinary skill). Further, each of these blocks mayalso interchangeably be referred to herein as “units” (e.g., coding treeunit (CTU), coding unit, prediction unit (PU), transform unit (TU), orthe like). In some cases, a unit may indicate a coding logical unit thatis encoded in a bitstream, while a block may indicate a portion of videoframe buffer a process is target to.

For inter-prediction modes, a video encoder can search for a blocksimilar to the block being encoded in a frame (or picture) located inanother temporal location, referred to as a reference frame or areference picture. The video encoder may restrict the search to acertain spatial displacement from the block to be encoded. A best matchmay be located using a two-dimensional (2D) motion vector that includesa horizontal displacement component and a vertical displacementcomponent. For intra-prediction modes, a video encoder may form thepredicted block using spatial prediction techniques based on data frompreviously encoded neighboring blocks within the same picture.

The video encoder may determine a prediction error. For example, theprediction can be determined as the difference between the pixel valuesin the block being encoded and the predicted block. The prediction errorcan also be referred to as the residual. The video encoder may alsoapply a transform to the prediction error (e.g., a discrete cosinetransform (DCT) or other suitable transform) to generate transformcoefficients. After transformation, the video encoder may quantize thetransform coefficients. The quantized transform coefficients and motionvectors may be represented using syntax elements and, along with controlinformation, form a coded representation of a video sequence. In someinstances, the video encoder may entropy code syntax elements, therebyfurther reducing the number of bits needed for their representation.

A video decoder may construct, using the syntax elements and controlinformation discussed above, predictive data (e.g., a predictive block)for decoding a current frame. For example, the video decoder may add thepredicted block and the compressed prediction error. The video decodermay determine the compressed prediction error by weighting the transformbasis functions using the quantized coefficients. The difference betweenthe reconstructed frame and the original frame is called reconstructionerror.

Film grain or granularity is the random optical texture of processedphotographic film. It is expensive to encode the film grain noise in theDCT domain. A film grain characteristics (FGC) supplemental enhancementinformation (SEI) message is specified in AVC, HEVC, and VVC to providea decoder with a parameterized model for film grain synthesis. Anencoder may use the FGC SEI message to characterize film grain that waspresent in the original source video material and was removed bypre-processing filtering techniques. While performing post-processing,the decoder may use the FGC SEI message to simulate the film grain onthe decoded images for the display process. The Society of MotionPicture and Television Engineers (SMPTE) Registered Disclosure Document(RDD) 5 provides film grain technology specifications for videobitstreams (e.g., H.264/AVC bistreams). The SMPTE RDD 5 Specification ishereby incorporated by reference in its entirety and for all purposes,and is provided in Appendix A included with the present application.

There can be challenges involved with film grain synthesis, which aredescribed in more detail below. Systems, apparatuses, processes (alsoreferred to as methods), and computer-readable media (collectivelyreferred to herein as “systems and techniques”) are described herein forimproving film grain synthesis. In some aspects, the systems andtechniques can provide a resolution adaptive film grain synthesis blocksize. Additionally or alternatively, in some aspects, the systems andtechniques can provide improvements to a film grain database.Additionally or alternatively, in some aspects, the systems andtechniques can provide grain pattern database generation. Additionaldetails will be described herein.

The systems and techniques described herein can be applied to any of theexisting video codecs, such as Versatile Video Coding (VVC), HighEfficiency Video Coding (HEVC), Advanced Video Coding (AVC), EssentialVideo Coding (EVC), VP9, the AV1 format/codec, and/or other video codingstandard, codec, format, etc. in development or to be developed.

FIG. 1 is a block diagram illustrating an example of a system 100including an encoding device 104 and a decoding device 112. The encodingdevice 104 may be part of a source device, and the decoding device 112may be part of a receiving device. The source device and/or thereceiving device may include an electronic device, such as a mobile orstationary telephone handset (e.g., smartphone, cellular telephone, orthe like), a desktop computer, a laptop or notebook computer, a tabletcomputer, a set-top box, a television, a camera, a display device, adigital media player, a video gaming console, a video streaming device,an Internet Protocol (IP) camera, or any other suitable electronicdevice. In some examples, the source device and the receiving device mayinclude one or more wireless transceivers for wireless communications.The coding techniques described herein are applicable to video coding invarious multimedia applications, including streaming video transmissions(e.g., over the Internet), television broadcasts or transmissions,encoding of digital video for storage on a data storage medium, decodingof digital video stored on a data storage medium, or other applications.As used herein, the term coding can refer to encoding and/or decoding.In some examples, system 100 can support one-way or two-way videotransmission to support applications such as video conferencing, videostreaming, video playback, video broadcasting, gaming, and/or videotelephony.

The encoding device 104 (or encoder) can be used to encode video datausing a video coding standard, format, codec, or protocol to generate anencoded video bitstream. Examples of video coding standards andformats/codecs include ITU-T H.261, ISO/IEC MPEG-1 Visual, ITU-T H.262or ISO/IEC MPEG-2 Visual, ITU-T H.263, ISO/IEC MPEG-4 Visual, ITU-TH.264 (also known as ISO/IEC MPEG-4 AVC), including its Scalable VideoCoding (SVC) and Multiview Video Coding (MVC) extensions, HighEfficiency Video Coding (HEVC) or ITU-T H.265, and Versatile VideoCoding (VVC) or ITU-T H.266. Various extensions to HEVC deal withmulti-layer video coding exist, including the range and screen contentcoding extensions, 3D video coding (3D-HEVC) and multiview extensions(MV-HEVC) and scalable extension (SHVC). The HEVC and its extensionshave been developed by the Joint Collaboration Team on Video Coding(JCT-VC) as well as Joint Collaboration Team on 3D Video CodingExtension Development (JCT-3V) of ITU-T Video Coding Experts Group(VCEG) and ISO/IEC Motion Picture Experts Group (MPEG). VP9, AOMediaVideo 1 (AV1) developed by the Alliance for Open Media Alliance of OpenMedia (AOMedia), and Essential Video Coding (EVC) are other video codingstandards for which the techniques described herein can be applied.

The techniques described herein can be applied to any of the existingvideo codecs (e.g., High Efficiency Video Coding (HEVC), Advanced VideoCoding (AVC), or other suitable existing video codec), and/or can be anefficient coding tool for any video coding standards being developedand/or future video coding standards, such as, for example, VVC and/orother video coding standard in development or to be developed. Forexample, examples described herein can be performed using video codecssuch as VVC, HEVC, AVC, and/or extensions thereof. However, thetechniques and systems described herein may also be applicable to othercoding standards, codecs, or formats, such as MPEG, JPEG (or othercoding standard for still images), EVC, VP9, AV1, extensions thereof, orother suitable coding standards already available or not yet availableor developed. For instance, in some examples, the encoding device 104and/or the decoding device 112 may operate according to a proprietaryvideo codec/format, such as AV1, extensions of AVI, and/or successorversions of AV1 (e.g., AV2), or other proprietary formats or industrystandards. Accordingly, while the techniques and systems describedherein may be described with reference to a particular video codingstandard, one of ordinary skill in the art will appreciate that thedescription should not be interpreted to apply only to that particularstandard.

Referring to FIG. 1 , a video source 102 may provide the video data tothe encoding device 104. The video source 102 may be part of the sourcedevice, or may be part of a device other than the source device. Thevideo source 102 may include a video capture device (e.g., a videocamera, a camera phone, a video phone, or the like), a video archivecontaining stored video, a video server or content provider providingvideo data, a video feed interface receiving video from a video serveror content provider, a computer graphics system for generating computergraphics video data, a combination of such sources, or any othersuitable video source.

The video data from the video source 102 may include one or more inputpictures or frames. A picture or frame is a still image that, in somecases, is part of a video. In some examples, data from the video source102 can be a still image that is not a part of a video. In HEVC, VVC,and other video coding specifications, a video sequence can include aseries of pictures. A picture may include three sample arrays, denotedSL, SCb, and SCr. SL is a two-dimensional array of luma samples, SCb isa two-dimensional array of Cb chrominance samples, and SCr is atwo-dimensional array of Cr chrominance samples. Chrominance samples mayalso be referred to herein as “chroma” samples. A pixel can refer to allthree components (luma and chroma samples) for a given location in anarray of a picture. In other instances, a picture may be monochrome andmay only include an array of luma samples, in which case the terms pixeland sample can be used interchangeably. With respect to exampletechniques described herein that refer to individual samples forillustrative purposes, the same techniques can be applied to pixels(e.g., all three sample components for a given location in an array of apicture). With respect to example techniques described herein that referto pixels (e.g., all three sample components for a given location in anarray of a picture) for illustrative purposes, the same techniques canbe applied to individual samples.

The encoder engine 106 (or encoder) of the encoding device 104 encodesthe video data to generate an encoded video bitstream. In some examples,an encoded video bitstream (or “video bitstream” or “bitstream”) is aseries of one or more coded video sequences. A coded video sequence(CVS) includes a series of access units (AUs) starting with an AU thathas a random access point picture in the base layer and with certainproperties up to and not including a next AU that has a random accesspoint picture in the base layer and with certain properties. Forexample, the certain properties of a random access point picture thatstarts a CVS may include a RASL flag (e.g., NoRaslOutputFlag) equalto 1. Otherwise, a random access point picture (with RASL flag equal to0) does not start a CVS. An access unit (AU) includes one or more codedpictures and control information corresponding to the coded picturesthat share the same output time. Coded slices of pictures areencapsulated in the bitstream level into data units called networkabstraction layer (NAL) units. For example, an HEVC video bitstream mayinclude one or more CVSs including NAL units. Each of the NAL units hasa NAL unit header. In one example, the header is one-byte for H.264/AVC(except for multi-layer extensions) and two-byte for HEVC. The syntaxelements in the NAL unit header take the designated bits and thereforeare visible to all kinds of systems and transport layers, such asTransport Stream, Real-time Transport (RTP) Protocol, File Format, amongothers.

Two classes of NAL units exist in the HEVC standard, including videocoding layer (VCL) NAL units and non-VCL NAL units. VCL NAL unitsinclude coded picture data forming a coded video bitstream. For example,a sequence of bits forming the coded video bitstream is present in VCLNAL units. A VCL NAL unit can include one slice or slice segment(described below) of coded picture data, and a non-VCL NAL unit includescontrol information that relates to one or more coded pictures. In somecases, a NAL unit can be referred to as a packet. An HEVC AU includesVCL NAL units containing coded picture data and non-VCL NAL units (ifany) corresponding to the coded picture data. Non-VCL NAL units maycontain parameter sets with high-level information relating to theencoded video bitstream, in addition to other information. For example,a parameter set may include a video parameter set (VPS), a sequenceparameter set (SPS), and a picture parameter set (PPS). In some cases,each slice or other portion of a bitstream can reference a single activePPS, SPS, and/or VPS to allow the decoding device 112 to accessinformation that may be used for decoding the slice or other portion ofthe bitstream.

NAL units may contain a sequence of bits forming a coded representationof the video data (e.g., an encoded video bitstream, a CVS of abitstream, or the like), such as coded representations of pictures in avideo. The encoder engine 106 generates coded representations ofpictures by partitioning each picture into multiple slices. A slice isindependent of other slices so that information in the slice is codedwithout dependency on data from other slices within the same picture. Aslice includes one or more slice segments including an independent slicesegment and, if present, one or more dependent slice segments thatdepend on previous slice segments.

In HEVC, the slices are then partitioned into coding tree blocks (CTBs)of luma samples and chroma samples. A CTB of luma samples and one ormore CTBs of chroma samples, along with syntax for the samples, arereferred to as a coding tree unit (CTU). A CTU may also be referred toas a “tree block” or a “largest coding unit” (LCU). A CTU is the basicprocessing unit for HEVC encoding. A CTU can be split into multiplecoding units (CUs) of varying sizes. A CU contains luma and chromasample arrays that are referred to as coding blocks (CBs).

The luma and chroma CBs can be further split into prediction blocks(PBs). A PB is a block of samples of the luma component or a chromacomponent that uses the same motion parameters for inter-prediction orintra-block copy (IBC) prediction (when available or enabled for use).The luma PB and one or more chroma PBs, together with associated syntax,form a prediction unit (PU). For inter-prediction, a set of motionparameters (e.g., one or more motion vectors, reference indices, or thelike) is signaled in the bitstream for each PU and is used forinter-prediction of the luma PB and the one or more chroma PBs. Themotion parameters can also be referred to as motion information. A CBcan also be partitioned into one or more transform blocks (TBs). A TBrepresents a square block of samples of a color component on which aresidual transform (e.g., the same two-dimensional transform in somecases) is applied for coding a prediction residual signal. A transformunit (TU) represents the TBs of luma and chroma samples, andcorresponding syntax elements. Transform coding is described in moredetail below.

A size of a CU corresponds to a size of the coding mode and may besquare in shape. For example, a size of a CU may be 8×8 samples, 16×16samples, 32×32 samples, 64×64 samples, or any other appropriate size upto the size of the corresponding CTU. The phrase “N×N” is used herein torefer to pixel dimensions of a video block in terms of vertical andhorizontal dimensions (e.g., 8 pixels×8 pixels). The pixels in a blockmay be arranged in rows and columns. In some implementations, blocks maynot have the same number of pixels in a horizontal direction as in avertical direction. Syntax data associated with a CU may describe, forexample, partitioning of the CU into one or more PUs. Partitioning modesmay differ between whether the CU is intra-prediction mode encoded orinter-prediction mode encoded. PUs may be partitioned to be non-squarein shape. Syntax data associated with a CU may also describe, forexample, partitioning of the CU into one or more TUs according to a CTU.A TU can be square or non-square in shape.

According to the HEVC standard, transformations may be performed usingtransform units (TUs). TUs may vary for different CUs. The TUs may besized based on the size of PUs within a given CU. The TUs may be thesame size or smaller than the PUs. In some examples, residual samplescorresponding to a CU may be subdivided into smaller units using aquadtree structure known as residual quad tree (RQT). Leaf nodes of theRQT may correspond to TUs. Pixel difference values associated with theTUs may be transformed to produce transform coefficients. The transformcoefficients may then be quantized by the encoder engine 106.

Once the pictures of the video data are partitioned into CUs, theencoder engine 106 predicts each PU using a prediction mode. Theprediction unit or prediction block is then subtracted from the originalvideo data to get residuals (described below). For each CU, a predictionmode may be signaled inside the bitstream using syntax data. Aprediction mode may include intra-prediction (or intra-pictureprediction) or inter-prediction (or inter-picture prediction).Intra-prediction utilizes the correlation between spatially neighboringsamples within a picture. For example, using intra-prediction, each PUis predicted from neighboring image data in the same picture using, forexample, DC prediction to find an average value for the PU, planarprediction to fit a planar surface to the PU, direction prediction toextrapolate from neighboring data, or any other suitable types ofprediction. Inter-prediction uses the temporal correlation betweenpictures in order to derive a motion-compensated prediction for a blockof image samples. For example, using inter-prediction, each PU ispredicted using motion compensation prediction from image data in one ormore reference pictures (before or after the current picture in outputorder). The decision whether to code a picture area using inter-pictureor intra-picture prediction may be made, for example, at the CU level.

The encoder engine 106 and decoder engine 116 (described in more detailbelow) may be configured to operate according to VVC. According to VVC,a video coder (such as encoder engine 106 and/or decoder engine 116)partitions a picture into a plurality of coding tree units (CTUs) (wherea CTB of luma samples and one or more CTBs of chroma samples, along withsyntax for the samples, are referred to as a CTU). The video coder canpartition a CTU according to a tree structure, such as a quadtree-binarytree (QTBT) structure or Multi-Type Tree (MTT) structure. The QTBTstructure removes the concepts of multiple partition types, such as theseparation between CUs, PUs, and TUs of HEVC. A QTBT structure includestwo levels, including a first level partitioned according to quadtreepartitioning, and a second level partitioned according to binary treepartitioning. A root node of the QTBT structure corresponds to a CTU.Leaf nodes of the binary trees correspond to coding units (CUs).

In an MTT partitioning structure, blocks may be partitioned using aquadtree partition, a binary tree partition, and one or more types oftriple tree partitions. A triple tree partition is a partition where ablock is split into three sub-blocks. In some examples, a triple treepartition divides a block into three sub-blocks without dividing theoriginal block through the center. The partitioning types in MTT (e.g.,quadtree, binary tree, and tripe tree) may be symmetrical orasymmetrical.

When operating according to the AV1 codec, video encoder engine 106 andvideo decoder engine 116 may be configured to code video data in blocks.In AV1, the largest coding block that can be processed is called asuperblock. In AV1, a superblock can be either 128×128 luma samples or64×64 luma samples. However, in successor video coding formats (e.g.,AV2), a superblock may be defined by different (e.g., larger) lumasample sizes. In some examples, a superblock is the top level of a blockquadtree. Video encoder engine 106 may further partition a superblockinto smaller coding blocks. Video encoder engine 106 may partition asuperblock and other coding blocks into smaller blocks using square ornon-square partitioning. Non-square blocks may include N/2×N, N×N/2,N/4×N, and N×N/4 blocks. Video encoder engine 106 and video decoderengine 116 may perform separate prediction and transform processes oneach of the coding blocks.

AV1 also defines a tile of video data. A tile is a rectangular array ofsuperblocks that may be coded independently of other tiles. That is,video encoder engine 106 and video decoder engine 116 may encode anddecode, respectively, coding blocks within a tile without using videodata from other tiles. However, video encoder engine 106 and videodecoder engine 116 may perform filtering across tile boundaries. Tilesmay be uniform or non-uniform in size. Tile-based coding may enablesparallel processing and/or multi-threading for encoder and decoderimplementations.

In some examples, the video coder can use a single QTBT or MTT structureto represent each of the luminance and chrominance components, while inother examples, the video coder can use two or more QTBT or MTTstructures, such as one QTBT or MTT structure for the luminancecomponent and another QTBT or MTT structure for both chrominancecomponents (or two QTBT and/or MTT structures for respective chrominancecomponents).

The video coder can be configured to use quadtree partitioning, QTBTpartitioning, MTT partitioning, superblock partitioning, or otherpartitioning structure.

In some examples, the one or more slices of a picture are assigned aslice type. Slice types include an intra-coded slice (I-slice), aninter-coded P-slice, and an inter-coded B-slice. An I-slice (intra-codedframes, independently decodable) is a slice of a picture that is onlycoded by intra-prediction, and therefore is independently decodablesince the I-slice requires only the data within the frame to predict anyprediction unit or prediction block of the slice. A P-slice(uni-directional predicted frames) is a slice of a picture that may becoded with intra-prediction and with uni-directional inter-prediction.Each prediction unit or prediction block within a P-slice is eithercoded with intra-prediction or inter-prediction. When theinter-prediction applies, the prediction unit or prediction block isonly predicted by one reference picture, and therefore reference samplesare only from one reference region of one frame. A B-slice(bi-directional predictive frames) is a slice of a picture that may becoded with intra-prediction and with inter-prediction (e.g., eitherbi-prediction or uni-prediction). A prediction unit or prediction blockof a B-slice may be bi-directionally predicted from two referencepictures, where each picture contributes one reference region and samplesets of the two reference regions are weighted (e.g., with equal weightsor with different weights) to produce the prediction signal of thebi-directional predicted block. As explained above, slices of onepicture are independently coded. In some cases, a picture can be codedas just one slice.

As noted above, intra-picture prediction of a picture utilizes thecorrelation between spatially neighboring samples within the picture.There is a plurality of intra-prediction modes (also referred to as“intra modes”). In some examples, the intra prediction of a luma blockincludes 35 modes, including the Planar mode, DC mode, and 33 angularmodes (e.g., diagonal intra prediction modes and angular modes adjacentto the diagonal intra prediction modes). The 35 modes of the intraprediction are indexed as shown in Table 1 below. In other examples,more intra modes may be defined including prediction angles that may notalready be represented by the 33 angular modes. In other examples, theprediction angles associated with the angular modes may be differentfrom those used in HEVC.

TABLE 1 Specification of intra prediction mode and associated namesIntra-prediction mode Associated name 0 INTRA_PLANAR 1 INTRA_DC 2 . . .34 INTRA_ANGULAR2 . . . INTRA_ANGULAR34

Inter-picture prediction uses the temporal correlation between picturesin order to derive a motion-compensated prediction for a current blockof image samples. Using a translational motion model, the position of ablock in a previously decoded picture (a reference picture) is indicatedby a motion vector (Δx, Δy), with Δx specifying the horizontaldisplacement and Δy specifying the vertical displacement of thereference block relative to the position of the current block. In somecases, a motion vector (Δx, Δy) can be in integer sample accuracy (alsoreferred to as integer accuracy), in which case the motion vector pointsto the integer-pel grid (or integer-pixel sampling grid) of thereference frame. In some cases, a motion vector (Δx, Δy) can be offractional sample accuracy (also referred to as fractional-pel accuracyor non-integer accuracy) to more accurately capture the movement of theunderlying object, without being restricted to the integer-pel grid ofthe reference frame. Accuracy of motion vectors may be expressed by thequantization level of the motion vectors. For example, the quantizationlevel may be integer accuracy (e.g., 1-pixel) or fractional-pel accuracy(e.g., ¼-pixel, ¼-pixel, or other sub-pixel value). Interpolation isapplied on reference pictures to derive the prediction signal when thecorresponding motion vector has fractional sample accuracy. For example,samples available at integer positions can be filtered (e.g., using oneor more interpolation filters) to estimate values at fractionalpositions. The previously decoded reference picture is indicated by areference index (refIdx) to a reference picture list. The motion vectorsand reference indices can be referred to as motion parameters. Two kindsof inter-picture prediction can be performed, including uni-predictionand bi-prediction.

With inter-prediction using bi-prediction (also referred to asbi-directional inter-prediction), two sets of motion parameters (Δx₀,y₀, refIdx₀ and Δx₁, y₁, refIdx₁) are used to generate two motioncompensated predictions (from the same reference picture or possiblyfrom different reference pictures). For example, with bi-prediction,each prediction block uses two motion compensated prediction signals,and generates B prediction units. The two motion compensated predictionsare then combined to get the final motion compensated prediction. Forexample, the two motion compensated predictions can be combined byaveraging. In another example, weighted prediction can be used, in whichcase different weights can be applied to each motion compensatedprediction. The reference pictures that can be used in bi-prediction arestored in two separate lists, denoted as list 0 and list 1. Motionparameters can be derived at the encoder using a motion estimationprocess.

With inter-prediction using uni-prediction (also referred to asuni-directional inter-prediction), one set of motion parameters (Δx₀,y₀, refIdx₀) is used to generate a motion compensated prediction from areference picture. For example, with uni-prediction, each predictionblock uses at most one motion compensated prediction signal, andgenerates P prediction units.

A PU may include the data (e.g., motion parameters or other suitabledata) related to the prediction process. For example, when the PU isencoded using intra-prediction, the PU may include data describing anintra-prediction mode for the PU. As another example, when the PU isencoded using inter-prediction, the PU may include data defining amotion vector for the PU. The data defining the motion vector for a PUmay describe, for example, a horizontal component of the motion vector(Δx), a vertical component of the motion vector (Δy), a resolution forthe motion vector (e.g., integer precision, one-quarter pixel precisionor one-eighth pixel precision), a reference picture to which the motionvector points, a reference index, a reference picture list (e.g., List0, List 1, or List C) for the motion vector, or any combination thereof.

AV1 includes two general techniques for encoding and decoding a codingblock of video data. The two general techniques are intra prediction(e.g., intra frame prediction or spatial prediction) and interprediction (e.g., inter frame prediction or temporal prediction). In thecontext of AV1, when predicting blocks of a current frame of video datausing an intra prediction mode, video encoder engine 106 and videodecoder engine 116 do not use video data from other frames of videodata. For most intra prediction modes, the video encoding device 104encodes blocks of a current frame based on the difference between samplevalues in the current block and predicted values generated fromreference samples in the same frame. The video encoding device 104determines predicted values generated from the reference samples basedon the intra prediction mode.

After performing prediction using intra- and/or inter-prediction, theencoding device 104 can perform transformation and quantization. Forexample, following prediction, the encoder engine 106 may calculateresidual values corresponding to the PU. Residual values may comprisepixel difference values between the current block of pixels being coded(the PU) and the prediction block used to predict the current block(e.g., the predicted version of the current block). For example, aftergenerating a prediction block (e.g., issuing inter-prediction orintra-prediction), the encoder engine 106 can generate a residual blockby subtracting the prediction block produced by a prediction unit fromthe current block. The residual block includes a set of pixel differencevalues that quantify differences between pixel values of the currentblock and pixel values of the prediction block. In some examples, theresidual block may be represented in a two-dimensional block format(e.g., a two-dimensional matrix or array of pixel values). In suchexamples, the residual block is a two-dimensional representation of thepixel values.

Any residual data that may be remaining after prediction is performed istransformed using a block transform, which may be based on discretecosine transform, discrete sine transform, an integer transform, awavelet transform, other suitable transform function, or any combinationthereof. In some cases, one or more block transforms (e.g., sizes 32×32,16×16, 8×8, 4×4, or other suitable size) may be applied to residual datain each CU. In some embodiments, a TU may be used for the transform andquantization processes implemented by the encoder engine 106. A given CUhaving one or more PUs may also include one or more TUs. As described infurther detail below, the residual values may be transformed intotransform coefficients using the block transforms, and then may bequantized and scanned using TUs to produce serialized transformcoefficients for entropy coding.

In some embodiments following intra-predictive or inter-predictivecoding using PUs of a CU, the encoder engine 106 may calculate residualdata for the TUs of the CU. The PUs may comprise pixel data in thespatial domain (or pixel domain). The TUs may comprise coefficients inthe transform domain following application of a block transform. Aspreviously noted, the residual data may correspond to pixel differencevalues between pixels of the unencoded picture and prediction valuescorresponding to the PUs. Encoder engine 106 may form the TUs includingthe residual data for the CU, and may then transform the TUs to producetransform coefficients for the CU.

The encoder engine 106 may perform quantization of the transformcoefficients. Quantization provides further compression by quantizingthe transform coefficients to reduce the amount of data used torepresent the coefficients. For example, quantization may reduce the bitdepth associated with some or all of the coefficients. In one example, acoefficient with an n-bit value may be rounded down to an m-bit valueduring quantization, with n being greater than m.

Once quantization is performed, the coded video bitstream includesquantized transform coefficients, prediction information (e.g.,prediction modes, motion vectors, block vectors, or the like),partitioning information, and any other suitable data, such as othersyntax data. The different elements of the coded video bitstream maythen be entropy encoded by the encoder engine 106. In some examples, theencoder engine 106 may utilize a predefined scan order to scan thequantized transform coefficients to produce a serialized vector that canbe entropy encoded. In some examples, encoder engine 106 may perform anadaptive scan. After scanning the quantized transform coefficients toform a vector (e.g., a one-dimensional vector), the encoder engine 106may entropy encode the vector. For example, the encoder engine 106 mayuse context adaptive variable length coding, context adaptive binaryarithmetic coding, syntax-based context-adaptive binary arithmeticcoding, probability interval partitioning entropy coding, or anothersuitable entropy encoding technique.

The output 110 of the encoding device 104 may send the NAL units makingup the encoded video bitstream data over the communications link 120 tothe decoding device 112 of the receiving device. The input 114 of thedecoding device 112 may receive the NAL units. The communications link120 may include a channel provided by a wireless network, a wirednetwork, or a combination of a wired and wireless network. A wirelessnetwork may include any wireless interface or combination of wirelessinterfaces and may include any suitable wireless network (e.g., theInternet or other wide area network, a packet-based network, WiFi™,radio frequency (RF), ultra-wideband (UWB), WiFi-Direct, cellular,Long-Term Evolution (LTE), WiMax™, or the like). A wired network mayinclude any wired interface (e.g., fiber, ethernet, powerline ethernet,ethernet over coaxial cable, digital signal line (DSL), or the like).The wired and/or wireless networks may be implemented using variousequipment, such as base stations, routers, access points, bridges,gateways, switches, or the like. The encoded video bitstream data may bemodulated according to a communication standard, such as a wirelesscommunication protocol, and transmitted to the receiving device.

In some examples, the encoding device 104 may store encoded videobitstream data in storage 108. The output 110 may retrieve the encodedvideo bitstream data from the encoder engine 106 or from the storage108. Storage 108 may include any of a variety of distributed or locallyaccessed data storage media. For example, the storage 108 may include ahard drive, a storage disc, flash memory, volatile or non-volatilememory, or any other suitable digital storage media for storing encodedvideo data. The storage 108 can also include a decoded picture buffer(DPB) for storing reference pictures for use in inter-prediction. In afurther example, the storage 108 can correspond to a file server oranother intermediate storage device that may store the encoded videogenerated by the source device. In such cases, the receiving deviceincluding the decoding device 112 can access stored video data from thestorage device via streaming or download. The file server may be anytype of server capable of storing encoded video data and transmittingthat encoded video data to the receiving device. Example file serversinclude a web server (e.g., for a website), an FTP server, networkattached storage (NAS) devices, or a local disk drive. The receivingdevice may access the encoded video data through any standard dataconnection, including an Internet connection. This may include awireless channel (e.g., a Wi-Fi connection), a wired connection (e.g.,DSL, cable modem, etc.), or a combination of both that is suitable foraccessing encoded video data stored on a file server. The transmissionof encoded video data from the storage 108 may be a streamingtransmission, a download transmission, or a combination thereof.

The input 114 of the decoding device 112 receives the encoded videobitstream data and may provide the video bitstream data to the decoderengine 116, or to storage 118 for later use by the decoder engine 116.For example, the storage 118 can include a DPB for storing referencepictures for use in inter-prediction. The receiving device including thedecoding device 112 can receive the encoded video data to be decoded viathe storage 108. The encoded video data may be modulated according to acommunication standard, such as a wireless communication protocol, andtransmitted to the receiving device. The communication medium fortransmitting the encoded video data can comprise any wireless or wiredcommunication medium, such as a radio frequency (RF) spectrum or one ormore physical transmission lines. The communication medium may form partof a packet-based network, such as a local area network, a wide-areanetwork, or a global network such as the Internet. The communicationmedium may include routers, switches, base stations, or any otherequipment that may be useful to facilitate communication from the sourcedevice to the receiving device.

The decoder engine 116 may decode the encoded video bitstream data byentropy decoding (e.g., using an entropy decoder) and extracting theelements of one or more coded video sequences making up the encodedvideo data. The decoder engine 116 may then rescale and perform aninverse transform on the encoded video bitstream data. Residual data isthen passed to a prediction stage of the decoder engine 116. The decoderengine 116 then predicts a current block of pixels (e.g., a PU). In someexamples, the prediction is added to the output of the inverse transform(the residual data).

The video decoding device 112 may output the decoded video to a videodestination device 122, which may include a display or other outputdevice for displaying the decoded video data to a consumer of thecontent. In some aspects, the video destination device 122 may be partof the receiving device that includes the decoding device 112. In someaspects, the video destination device 122 may be part of a separatedevice other than the receiving device.

In some embodiments, the video encoding device 104 and/or the videodecoding device 112 may be integrated with an audio encoding device andaudio decoding device, respectively. The video encoding device 104and/or the video decoding device 112 may also include other hardware orsoftware that is necessary to implement the coding techniques describedabove, such as one or more microprocessors, digital signal processors(DSPs), application specific integrated circuits (ASICs), fieldprogrammable gate arrays (FPGAs), discrete logic, software, hardware,firmware or any combinations thereof. The video encoding device 104 andthe video decoding device 112 may be integrated as part of a combinedencoder/decoder (codec) in a respective device.

The example system shown in FIG. 1 is one illustrative example that canbe used herein. Techniques for processing video data using thetechniques described herein can be performed by any digital videoencoding and/or decoding device. Although generally the techniques ofthis disclosure are performed by a video encoding device or a videodecoding device, the techniques may also be performed by a combinedvideo encoder-decoder, typically referred to as a “CODEC.” Moreover, thetechniques of this disclosure may also be performed by a videopreprocessor. The source device and the receiving device are merelyexamples of such coding devices in which the source device generatescoded video data for transmission to the receiving device. In someexamples, the source and receiving devices may operate in asubstantially symmetrical manner such that each of the devices includevideo encoding and decoding components. Hence, example systems maysupport one-way or two-way video transmission between video devices,e.g., for video streaming, video playback, video broadcasting, or videotelephony.

Extensions to the HEVC standard include the Multiview Video Codingextension, referred to as MV-HEVC, and the Scalable Video Codingextension, referred to as SHVC. The MV-HEVC and SHVC extensions sharethe concept of layered coding, with different layers being included inthe encoded video bitstream. Each layer in a coded video sequence isaddressed by a unique layer identifier (ID). A layer ID may be presentin a header of a NAL unit to identify a layer with which the NAL unit isassociated. In MV-HEVC, different layers usually represent differentviews of the same scene in the video bitstream. In SHVC, differentscalable layers are provided that represent the video bitstream indifferent spatial resolutions (or picture resolution) or in differentreconstruction fidelities. The scalable layers may include a base layer(with layer ID=0) and one or more enhancement layers (with layer IDs=1,2, . . . n). The base layer may conform to a profile of the firstversion of HEVC, and represents the lowest available layer in abitstream. The enhancement layers have increased spatial resolution,temporal resolution or frame rate, and/or reconstruction fidelity (orquality) as compared to the base layer. The enhancement layers arehierarchically organized and may (or may not) depend on lower layers. Insome examples, the different layers may be coded using a single standardcodec (e.g., all layers are encoded using HEVC, SHVC, or other codingstandard). In some examples, different layers may be coded using amulti-standard codec. For example, a base layer may be coded using AVC,while one or more enhancement layers may be coded using SHVC and/orMV-HEVC extensions to the HEVC standard.

In general, a layer includes a set of VCL NAL units and a correspondingset of non-VCL NAL units. The NAL units are assigned a particular layerID value. Layers can be hierarchical in the sense that a layer maydepend on a lower layer. A layer set refers to a set of layersrepresented within a bitstream that are self-contained, meaning that thelayers within a layer set can depend on other layers in the layer set inthe decoding process, but do not depend on any other layers fordecoding. Accordingly, the layers in a layer set can form an independentbitstream that can represent video content. The set of layers in a layerset may be obtained from another bitstream by operation of asub-bitstream extraction process. A layer set may correspond to the setof layers that is to be decoded when a decoder wants to operateaccording to certain parameters.

As previously described, an HEVC bitstream includes a group of NALunits, including VCL NAL units and non-VCL NAL units. VCL NAL unitsinclude coded picture data forming a coded video bitstream. For example,a sequence of bits forming the coded video bitstream is present in VCLNAL units. Non-VCL NAL units may contain parameter sets with high-levelinformation relating to the encoded video bitstream, in addition toother information. For example, a parameter set may include a videoparameter set (VPS), a sequence parameter set (SPS), and a pictureparameter set (PPS). Examples of goals of the parameter sets include bitrate efficiency, error resiliency, and providing systems layerinterfaces. Each slice references a single active PPS, SPS, and VPS toaccess information that the decoding device 112 may use for decoding theslice. An identifier (ID) may be coded for each parameter set, includinga VPS ID, an SPS ID, and a PPS ID. An SPS includes an SPS ID and a VPSID. A PPS includes a PPS ID and an SPS ID. Each slice header includes aPPS ID. Using the IDs, active parameter sets can be identified for agiven slice.

A PPS includes information that applies to all slices in a givenpicture. Because of this, all slices in a picture refer to the same PPS.Slices in different pictures may also refer to the same PPS. An SPSincludes information that applies to all pictures in a same coded videosequence (CVS) or bitstream. As previously described, a coded videosequence is a series of access units (AUs) that starts with a randomaccess point picture (e.g., an instantaneous decode reference (IDR)picture or broken link access (BLA) picture, or other appropriate randomaccess point picture) in the base layer and with certain properties(described above) up to and not including a next AU that has a randomaccess point picture in the base layer and with certain properties (orthe end of the bitstream). The information in an SPS may not change frompicture to picture within a coded video sequence. Pictures in a codedvideo sequence may use the same SPS. The VPS includes information thatapplies to all layers within a coded video sequence or bitstream. TheVPS includes a syntax structure with syntax elements that apply toentire coded video sequences. In some embodiments, the VPS, SPS, or PPSmay be transmitted in-band with the encoded bitstream. In someembodiments, the VPS, SPS, or PPS may be transmitted out-of-band in aseparate transmission than the NAL units containing coded video data.

This disclosure may generally refer to “signaling” certain information,such as syntax elements. The term “signaling” may generally refer to thecommunication of values for syntax elements and/or other data used todecode encoded video data. For example, the video encoding device 104may signal values for syntax elements in the bitstream. In general,signaling refers to generating a value in the bitstream. As noted above,video source 102 may transport the bitstream to video destination device122 substantially in real time, or not in real time, such as might occurwhen storing syntax elements to storage 108 for later retrieval by thevideo destination device 122.

A video bitstream can also include Supplemental Enhancement Information(SEI) messages. For example, an SEI NAL unit can be part of the videobitstream. In some cases, an SEI message can contain information that isnot needed by the decoding process. For example, the information in anSEI message may not be essential for the decoder to decode the videopictures of the bitstream, but the decoder can be use the information toimprove the display or processing of the pictures (e.g., the decodedoutput). The information in an SEI message can be embedded metadata. Inone illustrative example, the information in an SEI message could beused by decoder-side entities to improve the viewability of the content.In some instances, certain application standards may mandate thepresence of such SEI messages in the bitstream so that the improvementin quality can be brought to all devices that conform to the applicationstandard (e.g., the carriage of the frame-packing SEI message forframe-compatible plano-stereoscopic 3DTV video format, where the SEImessage is carried for every frame of the video, handling of a recoverypoint SEI message, use of pan-scan scan rectangle SEI message in DVB, inaddition to many other examples).

As noted above, film grain or granularity is the random optical textureof processed photographic film, and it can be expensive to encode filmgrain noise (e.g., in the DCT domain). The encoding device 104 (or otherdevice) may send a film grain characteristics (FGC) message (e.g., asspecified in AVC, HEVC, and VVC) to the decoding device 112. The FGCmessage provides the decoding device 112 with a parameterized model forfilm grain synthesis. The encoding device 104 may use the FGC message(e.g., by signalling information in the FGC message) to characterizefilm grain that was present in the original source video material andwas removed by pre-processing filtering techniques. The post-processingat the decoding device 112 may use the FGC SEI message to simulate thefilm grain on the decoded images for the display process.

The FGC SEI message enables the encoding device 104 to signal differentfilm grain simulation models, blending modes, bit-depths, transfercharacteristics, and chroma processing options. FIG. 2 is a diagram 200illustrating the film grain synthesis (e.g., simulation and blending)workflow for SMPTE RDD 5. The workflow can be accomplished by thefollowing steps (or any combination thereof in any suitable order):

-   -   1) Generate a database 202 of grain patterns. In one example,        the database 202 can include a collection of grain patterns        (e.g., up to 169 64×64 grain patterns), with each grain pattern        having a different combination of horizontal and vertical        cut-off frequencies;    -   2) Determine the intensity interval to which each current block        (e.g., the 8×8 current block of pixels being coded (the PU)),        from the decoder 214 in the decoded picture belongs by comparing        a representative luma value (e.g., by determining an average 204        luma value across the 8×8 current block) of each current block        to the upper and lower intensity interval bounds signaled in the        FGC SEI message;    -   3) Select a particular grain block (e.g., a particular 64×64        grain block) 206 from the database based on the cut-off        frequencies indicated for the corresponding intensity interval.        Then generate horizontal and vertical offsets within the        selected grain pattern (e.g., the selected 64×64 grain pattern),        such as using a pseudo-random process 208. Then select a grain        block specified by the offsets from the selected grain pattern        (e.g., select an 8×8 grain block specified by the offsets from        the 64×64 grain pattern).    -   4) Scale the sample values of the selected grain block (e.g.,        the selected 8×8 grain block) based on the grain strength        indicated for the corresponding intensity interval, and deblock        vertical grain block edges (e.g., deblock 210 vertical 8×8 grain        block edges).    -   5) Add 212 the sample value of the grain blocks and the sample        values of the corresponding decoded picture 216 current block to        produce the grain-blended output picture 218.

JVET-W0095 (ISO/IEC JTC 1/SC 29 JVET-W0095 to Sean McCarthy, et al.,“AHG9: Fixed-point grain blending process for film grain characteristicsSEI message,” July 2021) proposed a modification on SMPTE RDD 5 process.The JVET-W0095 document is hereby incorporated by reference in itsentirety and for all purposes, and is provided in Appendix B includedwith the present application. According to the proposal in JVET-W0095,the film grain block size is to increase from fixed 8×8 size in SMPTERDD 5 to 16×16 for picture resolutions greater than 1920×1080 and up to3840×2160 (4K), and 32×32 for resolution greater 4K including 8K. It isasserted that use of larger film grain block sizes for largerresolutions reduces implementation complexity and makes the grainpattern block size proportionally consistent across 2K, 4K, and 8Kresolutions.

There are potential challenges with the RDD 5 method and the proposedchanges of JVET-W0095 for hardware implementations. For example, onechallenge is that the calculation of average luma value of the currentblock requires line buffers in the implementation, and larger currentblock size means more line buffers. FIG. 3 is a diagram 300 illustratingan example of a line buffer needed for 8×8 or 16×16 block film grainsynthesis. As shown, an 8×8 current block 302 needs 8 line buffers(shown as line buffers 304A 0 to 7) and a 16×16 current block 306 needs16 line buffers 304B (collectively 304) (shown as line buffers 304B 0 to15). The line buffer 304 is a typical and major on-chip memory designfor image/video processing. The line buffer 304 typically occupies alarge on-chip circuit area. It is important to reduce the hardware costof the line buffer 304 through efficient design.

Another challenge is that the size of a film grain database (which is upto 169 64×64 grain patterns) is approximately 70 Kilobytes (KB), whichis also a high cost for the hardware implementation. The film graindatabase is a combination of horizontal and vertical cut-offfrequencies. The current grain database supports up to 13 horizontal andvertical cut-off frequencies. The trade-off between the database sizeand the subjective quality is to be explored to simplify the hardwareimplementation.

Yet another challenge is that the variable fgCoeffs[12][12][i][j] asproposed in JVET-W0095 only fills a 59×59 pseudo-random number insteadof 64×64, which may not cover all frequencies. According to JVET-W0095,the variable is derived as follows:

-   -   The variable fgCutFreqH[h] is set equal to ((h+3)<<2)−1, with        h=0 . . . 12.    -   The variable fgCutFreqV[v] is set equal to ((v+3)<<2)−1, with        v=0 . . . 12.    -   The variable fgCoeffs[h][v][i][j] is initially set equal to 0,        with h=0 . . . 12, v=0 . . . 12, i=0 . . . 63, j=0 . . . 63, and        is derived as follows:

for(h = 0; h < 13 , h++ ) {  for(v = 0; v < 13 , v++ ) {   prngVal =SeedLUT( h + 13 * v )   for( j = 0; j <= fgCutFreqV[ v ] ; j++ ) {   for( i = 0; i <= fgCutFreqH[ h ] ; i + = 4 ) {     for( k = 0; k < 4;k++ )      fgCoeffs[ h ][ v ][ i + k ][ j ] = gaussianLUT[ ( prngVal + k) % 2048 ]     prngVal = Prng( prngVal )    }   }   fgCoeffs[ h ][ v ][0 ][ 0 ] = 0  } }

Film grain metadata for use with AV1 is signaled via film grainparameters syntax (defined in “AV1 Bitstream & Decoding ProcessSpecification,” The Alliance for Open Media, Version 1.0.0 with Errata1, Jan. 18, 2019, hereby incorporated by reference in its entirety andfor all purposes) and film grain synthesis is part of mandatorypost-processing. If film grain parameters are presented in thebitstream, the film grain synthesis process is invoked withoutexception, and output video with a film grain is produced. While in AVC,HEVC, and VVC, film grain synthesis process is optional, the decoder maynot apply film grain synthesis even though an FGC SEI message is presentin the bitstream. One of the use cases of film grain is to provideimproved subjective quality at a lower bitrate for certain types ofvideo content by adding film grain noise in post-production to suppresscompression artifacts. In this case, the encoder may expect the filmgrain synthesis to be executed at the decoder side, which in some casesmay only be achieved by mandating the film grain synthesis by certainmeans.

In some cases, the film grain metadata is carried in or included in oneor more SEI messages associated with a particular bitstream. In suchcases, the decoder may need to scan all SEI messages to determine iffilm grain metadata is present for the associated bitstream. In someexamples, certain film grain metadata may be carried in user registeredby Recommendation ITU-T T.35 SEI message(s) with specific ITU-T T.35code. In such examples, the decoder may need to scan all T.35 codes todetermine whether the film grain metadata is present. An indicator offilm grain metadata availability would be beneficial to the decoderparsing process.

As noted above, systems and techniques are described herein forimproving film grain synthesis. In some aspects, the systems andtechniques can provide a resolution adaptive film grain synthesis blocksize. For example, because the film grain synthesis block height isrelevant to the number of line buffers, a resolution adaptive blockmethod is provided to change the film grain synthesis block height andwidth respectively depending on the picture height and width or thetotal number of picture pixel samples or a combination thereof. In somecases, the value of film grain synthesis block height shall be in therange of 1 to 8, inclusive. As a result, the maximum number of linebuffer used is the same as the RDD 5 process. In such cases, the valueof the film grain synthesis block width shall be in the range of 8 to W,inclusive, where W is the maximum width of the corresponding grainpattern.

FIGS. 4A and 4B are a flow diagram illustrating a process 400 for filmgrain synthesis, in accordance with aspects of the present disclosure.In the example process 400, the film grain synthesis block height may beset to one. A value for the maximum width of the corresponding grainpattern W may be a variable based on an overall picture resolution. Asan example, W may be set to 8 where the overall picture resolution isless than, or equal to, 1920×1080, W may be set to 16 where the overallpicture resolution 1920×1080 and up to 3840×2160 (4K), and W may be setto 32 where the overall picture resolution is greater than 4K including(or up to) 8K. In such a case, the film grain synthesis block size maybe set to 1×8 for over picture resolutions less than 1920×1080, 1×16 foroverall picture resolutions greater than 1920×1080 and up to 3840×2160(4K), and the film grain synthesis block size may set to 1×32 for theoverall picture resolution greater than 4K including (or up to) 8K. Insome cases, the value of W may be the same as a value of a width of thecurrent block.

In process 400 at step 402, a database of grain patterns may beobtained, the grain patterns of the database may have differentcombination of horizontal and vertical cut-off frequencies. At step 404,if there is an additional line (e.g., a row of pixels) in the currentblock, then execution proceeds to step 406. For example, an 8×8 currentblock may include 8 lines of 8 pixels.

At step 406, a 1×W block (e.g., line) of pixels from the current blockis obtained and stored in a memory. In some cases, this memory may be aportion of a line in a line buffer. In other cases, as a size of the 1×Wblock of pixel is relatively small, the block of pixels may be stored ina non-line buffer memory. Avoiding the use of a line buffer for filmgrain synthesis may help reduce or even eliminate a line buffer,potentially reducing hardware costs. At step 408, an average luma valuemay be determined for a 1×W block of pixels. This average luma value fora line may be stored in a memory. Execution may then return to step 404.Each line of the current block may be looped through to obtain and storean average luma value for each line of the current block. The averageluma values for the lines of the current block may be stored in anymemory. Execution may then proceed to step 410.

At step 410, an overall average luma value for the current block may bedetermined based on the average luma values for each line of the currentblock. For example, the overall average luma value may be determined byaveraging the average luma values for each line of the current block.

At step 412, an intensity level may be determined by comparing theoverall average luma value to an upper intensity interval bound and alower intensity interval bound signaled in the FGC SEI message. At step414, a grain pattern from the database of grain patterns is selectedbased on cut-off frequencies indicated by the comparison of the averageluma value to the intensity interval bounds.

At step 416, horizontal and vertical offsets are selected. In somecases, the horizontal and vertical offsets may be selected via a pseudorandom process. In some examples, when the width of the film grainsynthesis block is equal to the grain pattern width, the horizontaloffset used to select the block of the grain pattern can be set to 0.For example, where the width of the grain pattern width is less than thefilm grain synthesis block, a random horizontal offset may be used toplace the film grain into the film grain synthesis block during decodingof the video while avoiding a potentially noticeable pattern to the filmgrain by a viewer. However, if the grain pattern has the same width asthe film grain synthesis block, then no horizontal offset may beapplied.

At step 418, a grain block from the grain pattern is selected based onthe horizontal and vertical offsets from the selected grain pattern. Insome cases, the grain block is selected for application to the currentblock and the grain block may be selected based on a first line ofpixels of the current block.

At step 420, the selected grain block is scaled based on the grainstrength indicated for the corresponding intensity interval, and deblockvertical grain block edges. At step 422, the scaled sample value (e.g.,scaled grain block) is added to a decoded current block to produce anoutput picture including synthesized film grain.

As another example, the film grain synthesis block size may set to 8×16for the overall picture resolution greater than 1920×1080 and up to3840×2160 (4K), and the film grain synthesis block size may set to 8×32for the overall picture resolution greater than 4K including (or up to)8K.

Additionally or alternatively, in some aspects, the systems andtechniques can provide improvements to a film grain database. Accordingto such aspects, the current 169 64×64 grain pattern may be reduced tosave in hardware implementation storage since the database is usuallypre-calculated and stored in the memory. In one example, a method isprovided to reduce the cut-off frequency, in which case the number ofcut-off frequencies may be reduced from 13 to 7 (e.g., 7 horizontalcut-off frequencies and 7 vertical cut-off frequencies), which reducesthe grain database size to 49 64×64 grain pattens and storage capacityto approximately 20 KB. According to such an example, the derivation ofthe variables fgCutFreqH[h], fgCutFreqV[v] and fgCoeffs[h][v][i][j], asproposed in NET-W0095, are modified as follows (with changes shown in

):

-   -   The variable fgCutFreqH[h] is set equal to ((h+        )<<        )−5, with h=0        .    -   The variable fgCutFreqV[v] is set equal to ((v+        )<<        )−5, with v=0        .    -   The variable fgCoeffs[h][v][i][j] is initially set equal to 0,        with h=0        , v=0        , i=0 . . . 63, j=0 . . . 63, and is derived as follows:

for(h = 0; h < 

  , h++ ) {  for(v = 0; v < 

  , v++ ) {   prngVal = SeedLUT( 

  h + 

  v )   for( j = 0; j <= fgCutFreqV[ v ] ; j++ ) {    for( i = 0; i <=fgCutFreqH[ h ] ; i + = 

 ) {     for( k = 0; k <

; k++ )      fgCoeffs[ h ][ v ][ i + k ][ j ] = gaussianLUT[ ( prngVal +k ) % 2048 ]     prngVal = Prng( prngVal )    }   }   fgCoeffs[ h ][ v][ 0 ][ 0 ] = 0  } }

SMPTE RDD 5 specifies that the value of the FGC SEI message syntaxelements comp_model_value[c][i][1] and comp_model_value[c][i][2] shallbe in the range of 2 to 14 based on 13 horizontal and vertical cut-offfrequency. According to aspects described herein, the grain blockblending process may be modified to accommodate reduced number ofcut-off frequency as follows (with changes shown in

):

The variable intensity IntevalIdx for the current block is initializedto be −1 and is derived as follows:

sumBlock = 0 avgRatio = Log2( BlockSize / 8) for( i = 0; i < BlockSize ;i++ )   for( j = 0; j < BlockSize ; j++ )      sumBlock += decSamples[Min( picWidth − 1, xCurr + i ) ][ Min( picHeight − 1, y     Curr + j ) ](xx) b_(avg) = Clip3( 0, 255, ( sumBlock + ( 1 << ( fgBitDepth[ cIdx ] +2 * avgRatio − 3 ) ) ) >> ( fgBitDepth[ cIdx ] + 2 * avgRatio − 2 ) for( i = 0; i <= fg_num_intensity_intervals_minus1[ cIdx ]; i++ )   if(b_(avg) >= fg_intensity_interval_lower_bound[ cIdx ][ i ] &&     b_(avg) <= fg_intensity_interval_upper_bound[ cIdx ][ i ] ) {   intensityIntervalIdx = i 

(xx)    break   }

In another example, a method is provided to reduce the grain patternsize from 64×64 to 32×32, in which case the size of the grain databaseis 169 32×32 with the same number of cut-off frequency, the storagecapacity is approximately 17 KB. In such an example, the derivation ofvariables fgCutFreqH[h], fgCutFreqV[v] and fgCoeffs[h][v][i][j], asproposed in NET-W0095, are modified as follows (with changes shown in

):

-   -   The variable fgCutFreqH[h] is set equal to ((h+3)<<        )−1, with h=0 . . . 12.    -   The variable fgCutFreqV[v] is set equal to ((v+3)<<        )−1, with v=0 . . . 12.    -   The variable fgCoeffs[h][v][i][j] is initially set equal to 0,        with h=0 . . . 12, v=0 . . . 12, i=0        , j=0        , and is derived as follows:

for(h = 0; h < 13 , h++ ) {  for(v = 0; v < 13 , v++ ) {   prngVal =SeedLUT( h + 13 * v )   for( j = 0; j <= fgCutFreqV[ v ] ; j++ ) {   for( i = 0; i <= fgCutFreqH[ h ]; i + = 

 ) {     for( k = 0; k < 

; k++ )      fgCoeffs[ h ][ v ][ i + k ][ j ] = gaussianLUT[ ( prngVal +k ) % 2048 ]     prngVal = Prng( prngVal )    }   }   fgCoeffs[ h ][ v][ 0 ][ 0 ] = 0  } }

In some aspects, the grain pattern database size may be reduced byreducing grain pattern size from 64×64 to 32×32 and the number ofcut-off frequencies from 13 to 7. The total storage is reduced to 5 KB.In such aspects, the derivation of variables fgCutFreqH[h],fgCutFreqV[v] and fgCoeffs[h][v][i][j], as proposed in NET-W0095, aremodified as follows (with changes shown in

):

-   -   The variable fgCutFreqH[h] is set equal to ((h+        )<<2)−1, with h=0    -   The variable fgCutFreqV[v] is set equal to ((v+        )<<2)−1, with v=0        .    -   The variable fgCoeffs[h][v][i][j] is initially set equal to 0,        with h=0        v=        i=0        j=0        , and is derived as follows:

for(h = 0; h < 13 , h++ ) {  for(v = 0; v < 13 , v++ ) {   prngVal =SeedLUT( 

 h + 

  v )   for( j = 0; j <= fgCutFreqV[ v ] ; j++ ) {    for( i = 0; i <=fgCutFreqH[ h ] ; i + = 4 ) {     for( k = 0; k < 4; k++ )     fgCoeffs[ h ][ v ][ i + k ][ j ] = gaussianLUT[ ( prngVal + k ) %2048 ]     prngVal = Prng( prngVal )    }   }   fgCoeffs[ h ][ v ][ 0 ][0 ] = 0  } }

In some examples, in cases when the grain pattern size is reduced to32×32, the maximum width of the corresponding film grain synthesis blockis 32.

Additionally or alternatively, in some aspects, the systems andtechniques can provide grain pattern database generation. The grainpattern database generation proposed in JVET-W0095 does not cover allfrequencies, as the variable fgCoeffs[12][12][i][j] only fills a 59×59pseudo-random number. According to one example, the derivation providedin JVET-W0095 is modified as follows to cover all frequencies (withchanges shown in

).

-   -   The variable fgCutFreqH[h] is set equal to ((h+        )<<2)−1, with h=0 . . . 12.    -   The variable fgCutFreqV[v] is set equal to ((v+        )<<2)−1, with v=0 . . . 12.    -   The variable fgCoeffs[h][v][i][j] is initially set equal to 0,        with h=0 . . . 12, v=0 . . . 12, i=0 . . . 63, j=0 . . . 63, and        is derived as follows:

for(h = 0; h < 13 , h++ ) {  for(v = 0; v < 13 , v++ ) {   prngVal =SeedLUT( h + 13 * v )   for( j = 0; j <= fgCutFreqV[ v ] ; j++ ) {   for( i = 0; i <= fgCutFreqH[ h ] ; i + = 4 ) {     for( k = 0; k < 4;k++ )      fgCoeffs[ h ][ v ][ i + k ][ j ] = gaussianLUT[ ( prngVal + k) % 2048 ]     prngVal = Prng( prngVal )    }   }   fgCoeffs[ h ][ v ][0 ][ 0 ] = 0  } }

Additionally or alternatively, in some aspects, the systems andtechniques can provide one or more approaches to perform (and in somecases mandate) film grain synthesis. In some aspects, a syntax element(which can be referred to film grain application syntax element) may beadded to a parameter set, such as a sequence parameter set (SPS),picture parameter set (PPS), picture header, or other field or parameterset. In some cases, the proposed syntax element mandates the presence ofthe FGC SEI message. Additionally or alternatively, in some cases, theproposed syntax element mandates the film grain synthesis applied to theassociated coded video sequence or picture. For instance, the proposedsyntax element may mandate the presence of the FGC SEI message and alsomandate the film grain synthesis applied to the associated coded videosequence or picture.

In some illustrative aspects, for existing video codec such as VVC orother existing codec, the relevant film grain application syntax elementmay be added to a reserved extension field. One illustrative example isto add a film grain application syntax element, which can be denoted assps_fg_apply_flag, in the SPS extension field as follows (with changesshown in

):

if( sps_extension_flag ) {  sps _(—) range _(—) extension _(—) flag u(1) 

 

 sps _(—) extension 

 bits u( 

 )  if( sps_range_extension_flag )   sps_range_extension( ) } if(sps_extension_7bits )  while( more_rbsp_data( ) )  sps_extension_data_flag u(1) rbsp_trailing_bits( )

An illustrative example of semantics for the newsps_film_grain_apply_flag syntax element is as follows:sps_film_grain_apply_flag equal to 1 specifies that there shall be atleast one FGC SEI message present in the associated bitstream and thefilm grain synthesis shall be applied to the associated CLVS.sps_film_grain_apply_flag equal to 0 does not impose such a constraint.

In some illustrative aspects, a film grain application syntax elementmay be added to video usability information (VUI) payload extensionfield as follows (with changes shown in

):

Descriptor vui_payload( payloadSize ) {  VuiExtensionBitsPresentFlag = 0 vui_parameters( payloadSize ) /* Specified in Rec. ITU-T H.274 |ISO/IEC 23002-7 */  if( VuiExtensionBitsPresentFlag | | more_data_in_payload( ) ) {   if( payload_extension_present( ) ) 

   

 

   vui _(—) reserved _(—) payload _(—) extension _(—) data u(v)   

  vui _(—) payload _(—) bit _(—) equal _(—) to _(—) one /* equal to 1 */f(1)   while( !byte_aligned( ) )    vui _(—) payload _(—) bit _(—) equal_(—) to _(—) zero /* equal to 0 */ f(1)  } }

An illustrative example of semantics for the newvui_film_grain_apply_flag syntax element is as follows:vui_film_grain_apply_flag equal to 1 specifies that there shall be atleast one FGC SEI message present in the associated bitstream and thefilm grain synthesis shall be applied to the associated CLVS.vui_film_grain_apply_flag equal to 0 does not impose such a constraint.

Additionally or alternatively, in some aspects, the systems andtechniques can provide a film grain constraint indicator. As describedpreviously, an indicator of film grain metadata availability would bebeneficial to the decoder parsing process in some cases (e.g., when thefilm grain metadata is included in one or more SEI messages, in one ormore user registered by Recommendation ITU-T T.35 SEI messages withspecific ITU-T T.35 code, and/or other cases). The film grain constraintindicator may indicate the film grain metadata availability of theassociated bitstream.

In some cases, the indicator may be signaled in one or more syntaxelements or structures (e.g., in a general constraints informationsyntax, such as general_constraints_info( )) syntax of VVC or othercodec or video coding standard or format) or in one or more parameters(e.g., in Video usability information (VUI) parameters). Oneillustrative example of a VUI film grain indicator is provided below ina film grain constraint syntax element denoted asvui_non_film_grain_constraint_flag (with changes shown in

):

Descriptor vui_parameters( payloadSize ) {  vui _(—) progressive _(—)source _(—) flag u(1)  vui _(—) interlaced _(—) source _(—) flag u(1) vui _(—) non _(—) packed _(—) constraint _(—) flag u(1)  vui _(—) non_(—) projected _(—) constraint _(—) flag u(1)  

 

 

u(1) ... }

An illustrative example of semantics for the newvui_non_film_grain_constraint_flag syntax element is as follows:vui_non_film_grain_constraint_flag equal to 1 specifies that there shallnot be any film grain characteristics SEI message, or any user dataregistered by Recommendation ITU-T T.35 SEI message carrying film grainmetadata present in the bitstream that apply to the CLVS.vui_non_film_grain_constraint_flag equal to 0 does not impose such aconstraint.

FIG. 5 is a flow diagram illustrating an example of a process 500 forprocessing video data, in accordance with aspects of the presentdisclosure. The process 500 may be performed by a computing device (orapparatus) or a component (e.g., a chipset, codec, etc.) of thecomputing device. The computing device may be a mobile device (e.g., amobile phone), a network-connected wearable such as a watch, an extendedreality (XR) device such as a virtual reality (VR) device or augmentedreality (AR) device, a vehicle or component or system of a vehicle, orother type of computing device. In some cases, the computing device maybe or may include coding device, such as the encoding device 104, thedecoding device 112, or a combined encoding device (or codec). Theoperations of the process 500 may be implemented as software componentsthat are executed and run on one or more processors.

At block 502, the computing device (or component thereof) may obtainvideo data including a picture. At block 504, the computing device (orcomponent thereof) may determine a width of a film grain synthesis blockof the picture based on at least one of a width and a height of thepicture. In some cases, a width value for the film grain synthesis blockis in a range of 8 to W, inclusive, where W is a maximum width of acorresponding grain pattern. In some cases, the computing device (orcomponent thereof) may determine at least one of the width and theheight of the film grain synthesis block of the picture based on atleast one of the width and the height of the picture, and computingdevice (or component thereof) may determine the width of the film grainsynthesis block of the picture based the width and the height of thepicture.

At block 506, the computing device (or component thereof) may determinea height of the film grain synthesis block of the picture is one. Atblock 508, the computing device (or component thereof) may determine ablock size of the film grain synthesis block based on the determinedwidth and height.

At block 510, the computing device (or component thereof) may select agrain block based on the determined block size. In some cases, thecomputing device (or component thereof) may obtain a current block ofsamples from the picture, obtain a set of pixels from the current blockof samples based on the determined block size, and determine an averageluma value for the set of pixels, wherein to select the grain block, thecomputing device (or component thereof) may select the grain block basedon the average luma value. In some cases, the set of pixels comprises aline of pixels from the current block of samples and the computingdevice (or component thereof) may determine the average luma value foreach line of pixels for the current block of samples, determine anoverall average luma value for the current block of samples based on theaverage luma value for each line of pixels, and determine an intensitylevel based on the overall average luma value. In some cases, thecomputing device (or component thereof) may select a grain pattern basedon the intensity level, randomly select at least a vertical offset,wherein to select the grain block, and select the grain block from thegrain pattern based on the vertical offset. In some cases, the computingdevice (or component thereof) may decode the current block of samples,add the selected grain block to the decoded current block of samples togenerate an output current block, and output the output current block.In some cases, the computing device (or component thereof) may determinea width of the film grain synthesis block is equal to a width of acorresponding grain pattern, and set a horizontal offset used to selecta block of the grain pattern to 0.

The processes (or methods) described herein can be used individually orin any combination. In some implementations, the processes (or methods)described herein can be performed by a computing device or an apparatus,such as the system 100 shown in FIG. 1 . For example, the processes canbe performed by the encoding device 104 shown in FIG. 1 and FIG. 6 , byanother video source-side device or video transmission device, by thedecoding device 112 shown in FIG. 1 and FIG. 7 , and/or by anotherclient-side device, such as a player device, a display, or any otherclient-side device. In some cases, the computing device or apparatus mayinclude one or more input devices, one or more output devices, one ormore processors, one or more microprocessors, one or moremicrocomputers, and/or other component(s) that is/are configured tocarry out the steps of one or more processes described herein.

In some examples, the computing device may include a mobile device, adesktop computer, a server computer and/or server system, or other typeof computing device. The components of the computing device (e.g., theone or more input devices, one or more output devices, one or moreprocessors, one or more microprocessors, one or more microcomputers,and/or other component) can be implemented in circuitry. For example,the components can include and/or can be implemented using electroniccircuits or other electronic hardware, which can include one or moreprogrammable electronic circuits (e.g., microprocessors, graphicsprocessing units (GPUs), digital signal processors (DSPs), centralprocessing units (CPUs), and/or other suitable electronic circuits),and/or can include and/or be implemented using computer software,firmware, or any combination thereof, to perform the various operationsdescribed herein. In some examples, the computing device or apparatusmay include a camera configured to capture video data (e.g., a videosequence) including video frames. In some examples, a camera or othercapture device that captures the video data is separate from thecomputing device, in which case the computing device receives or obtainsthe captured video data. The computing device may include a networkinterface configured to communicate the video data. The networkinterface may be configured to communicate Internet Protocol (IP) baseddata or other type of data. In some examples, the computing device orapparatus may include a display for displaying output video content,such as samples of pictures of a video bitstream.

The processes can be described with respect to logical flow diagrams,the operation of which represent a sequence of operations that can beimplemented in hardware, computer instructions, or a combinationthereof. In the context of computer instructions, the operationsrepresent computer-executable instructions stored on one or morecomputer-readable storage media that, when executed by one or moreprocessors, perform the recited operations. Generally,computer-executable instructions include routines, programs, objects,components, data structures, and the like that perform particularfunctions or implement particular data types. The order in which theoperations are described is not intended to be construed as alimitation, and any number of the described operations can be combinedin any order and/or in parallel to implement the processes.

Additionally, the processes may be performed under the control of one ormore computer systems configured with executable instructions and may beimplemented as code (e.g., executable instructions, one or more computerprograms, or one or more applications) executing collectively on one ormore processors, by hardware, or combinations thereof. As noted above,the code may be stored on a computer-readable or machine-readablestorage medium, for example, in the form of a computer programcomprising a plurality of instructions executable by one or moreprocessors. The computer-readable or machine-readable storage medium maybe non-transitory.

The coding techniques discussed herein may be implemented in an examplevideo encoding and decoding system (e.g., system 100). In some examples,a system includes a source device that provides encoded video data to bedecoded at a later time by a destination device. In particular, thesource device provides the video data to destination device via acomputer-readable medium. The source device and the destination devicemay comprise any of a wide range of devices, including desktopcomputers, notebook (i.e., laptop) computers, tablet computers, set-topboxes, telephone handsets such as so-called “smart” phones, so-called“smart” pads, televisions, cameras, display devices, digital mediaplayers, video gaming consoles, video streaming device, or the like. Insome cases, the source device and the destination device may be equippedfor wireless communication.

The destination device may receive the encoded video data to be decodedvia the computer-readable medium. The computer-readable medium maycomprise any type of medium or device capable of moving the encodedvideo data from source device to destination device. In one example,computer-readable medium may comprise a communication medium to enablesource device to transmit encoded video data directly to destinationdevice in real-time. The encoded video data may be modulated accordingto a communication standard, such as a wireless communication protocol,and transmitted to destination device. The communication medium maycomprise any wireless or wired communication medium, such as a radiofrequency (RF) spectrum or one or more physical transmission lines. Thecommunication medium may form part of a packet-based network, such as alocal area network, a wide-area network, or a global network such as theInternet. The communication medium may include routers, switches, basestations, or any other equipment that may be useful to facilitatecommunication from source device to destination device.

In some examples, encoded data may be output from output interface to astorage device. Similarly, encoded data may be accessed from the storagedevice by input interface. The storage device may include any of avariety of distributed or locally accessed data storage media such as ahard drive, Blu-ray discs, DVDs, CD-ROMs, flash memory, volatile ornon-volatile memory, or any other suitable digital storage media forstoring encoded video data. In a further example, the storage device maycorrespond to a file server or another intermediate storage device thatmay store the encoded video generated by source device. Destinationdevice may access stored video data from the storage device viastreaming or download. The file server may be any type of server capableof storing encoded video data and transmitting that encoded video datato the destination device. Example file servers include a web server(e.g., for a website), an FTP server, network attached storage (NAS)devices, or a local disk drive. Destination device may access theencoded video data through any standard data connection, including anInternet connection. This may include a wireless channel (e.g., a Wi-Ficonnection), a wired connection (e.g., DSL, cable modem, etc.), or acombination of both that is suitable for accessing encoded video datastored on a file server. The transmission of encoded video data from thestorage device may be a streaming transmission, a download transmission,or a combination thereof.

The techniques of this disclosure are not necessarily limited towireless applications or settings. The techniques may be applied tovideo coding in support of any of a variety of multimedia applications,such as over-the-air television broadcasts, cable televisiontransmissions, satellite television transmissions, Internet streamingvideo transmissions, such as dynamic adaptive streaming over HTTP(DASH), digital video that is encoded onto a data storage medium,decoding of digital video stored on a data storage medium, or otherapplications. In some examples, system may be configured to supportone-way or two-way video transmission to support applications such asvideo streaming, video playback, video broadcasting, and/or videotelephony.

In one example the source device includes a video source, a videoencoder, and a output interface. The destination device may include aninput interface, a video decoder, and a display device. The videoencoder of source device may be configured to apply the techniquesdisclosed herein. In other examples, a source device and a destinationdevice may include other components or arrangements. For example, thesource device may receive video data from an external video source, suchas an external camera. Likewise, the destination device may interfacewith an external display device, rather than including an integrateddisplay device.

The example system above is merely one example. Techniques forprocessing video data in parallel may be performed by any digital videoencoding and/or decoding device. Although generally the techniques ofthis disclosure are performed by a video encoding device, the techniquesmay also be performed by a video encoder/decoder, typically referred toas a “CODEC.” Moreover, the techniques of this disclosure may also beperformed by a video preprocessor. Source device and destination deviceare merely examples of such coding devices in which source devicegenerates coded video data for transmission to destination device. Insome examples, the source and destination devices may operate in asubstantially symmetrical manner such that each of the devices includevideo encoding and decoding components. Hence, example systems maysupport one-way or two-way video transmission between video devices,e.g., for video streaming, video playback, video broadcasting, or videotelephony.

The video source may include a video capture device, such as a videocamera, a video archive containing previously captured video, and/or avideo feed interface to receive video from a video content provider. Asa further alternative, the video source may generate computergraphics-based data as the source video, or a combination of live video,archived video, and computer-generated video. In some cases, if videosource is a video camera, source device and destination device may formso-called camera phones or video phones. As mentioned above, however,the techniques described in this disclosure may be applicable to videocoding in general, and may be applied to wireless and/or wiredapplications. In each case, the captured, pre-captured, orcomputer-generated video may be encoded by the video encoder. Theencoded video information may then be output by output interface ontothe computer-readable medium.

As noted the computer-readable medium may include transient media, suchas a wireless broadcast or wired network transmission, or storage media(that is, non-transitory storage media), such as a hard disk, flashdrive, compact disc, digital video disc, Blu-ray disc, or othercomputer-readable media. In some examples, a network server (not shown)may receive encoded video data from the source device and provide theencoded video data to the destination device, e.g., via networktransmission. Similarly, a computing device of a medium productionfacility, such as a disc stamping facility, may receive encoded videodata from the source device and produce a disc containing the encodedvideo data. Therefore, the computer-readable medium may be understood toinclude one or more computer-readable media of various forms, in variousexamples.

The input interface of the destination device receives information fromthe computer-readable medium. The information of the computer-readablemedium may include syntax information defined by the video encoder,which is also used by the video decoder, that includes syntax elementsthat describe characteristics and/or processing of blocks and othercoded units, e.g., group of pictures (GOP). A display device displaysthe decoded video data to a user, and may comprise any of a variety ofdisplay devices such as a cathode ray tube (CRT), a liquid crystaldisplay (LCD), a plasma display, an organic light emitting diode (OLED)display, or another type of display device. Various embodiments of theapplication have been described.

Specific details of the encoding device 104 and the decoding device 112are shown in FIG. 6 and FIG. 7 , respectively. FIG. 6 is a block diagramillustrating an example encoding device 104 that may implement one ormore of the techniques described in this disclosure. Encoding device 104may, for example, generate the syntax elements and/or structuresdescribed herein (e.g., the syntax elements and/or structures of a greenmetadata, such as Complexity Metrics (CM), or other syntax elementsand/or structures). Encoding device 104 may perform intra-prediction andinter-prediction coding of video blocks within video slices, tiles,sub-pictures, etc. As previously described, intra-coding relies, atleast in part, on spatial prediction to reduce or remove spatialredundancy within a given video frame or picture. Inter-coding relies,at least in part, on temporal prediction to reduce or remove temporalredundancy within adjacent or surrounding frames of a video sequence.Intra-mode (I mode) may refer to any of several spatial basedcompression modes. Inter-modes, such as uni-directional prediction (Pmode) or bi-prediction (B mode), may refer to any of severaltemporal-based compression modes.

The encoding device 104 includes a partitioning unit 35, predictionprocessing unit 41, filter unit 63, picture memory 64, summer 50,transform processing unit 52, quantization unit 54, and entropy encodingunit 56. Prediction processing unit 41 includes motion estimation unit42, motion compensation unit 44, and intra-prediction processing unit46. For video block reconstruction, encoding device 104 also includesinverse quantization unit 58, inverse transform processing unit 60, andsummer 62. Filter unit 63 is intended to represent one or more loopfilters such as a deblocking filter, an adaptive loop filter (ALF), anda sample adaptive offset (SAO) filter. Although filter unit 63 is shownin FIG. 6 as being an in loop filter, in other configurations, filterunit 63 may be implemented as a post loop filter. A post processingdevice 57 may perform additional processing on encoded video datagenerated by the encoding device 104. The techniques of this disclosuremay in some instances be implemented by the encoding device 104. Inother instances, however, one or more of the techniques of thisdisclosure may be implemented by post processing device 57.

As shown in FIG. 6 , the encoding device 104 receives video data, andpartitioning unit 35 partitions the data into video blocks. Thepartitioning may also include partitioning into slices, slice segments,tiles, or other larger units, as wells as video block partitioning,e.g., according to a quadtree structure of LCUs and CUs. The encodingdevice 104 generally illustrates the components that encode video blockswithin a video slice to be encoded. The slice may be divided intomultiple video blocks (and possibly into sets of video blocks referredto as tiles). Prediction processing unit 41 may select one of aplurality of possible coding modes, such as one of a plurality ofintra-prediction coding modes or one of a plurality of inter-predictioncoding modes, for the current video block based on error results (e.g.,coding rate and the level of distortion, or the like). Predictionprocessing unit 41 may provide the resulting intra- or inter-coded blockto summer 50 to generate residual block data and to summer 62 toreconstruct the encoded block for use as a reference picture.

Intra-prediction processing unit 46 within prediction processing unit 41may perform intra-prediction coding of the current video block relativeto one or more neighboring blocks in the same frame or slice as thecurrent block to be coded to provide spatial compression. Motionestimation unit 42 and motion compensation unit 44 within predictionprocessing unit 41 perform inter-predictive coding of the current videoblock relative to one or more predictive blocks in one or more referencepictures to provide temporal compression.

Motion estimation unit 42 may be configured to determine theinter-prediction mode for a video slice according to a predeterminedpattern for a video sequence. The predetermined pattern may designatevideo slices in the sequence as P slices, B slices, or GPB slices.Motion estimation unit 42 and motion compensation unit 44 may be highlyintegrated, but are illustrated separately for conceptual purposes.Motion estimation, performed by motion estimation unit 42, is theprocess of generating motion vectors, which estimate motion for videoblocks. A motion vector, for example, may indicate the displacement of aprediction unit (PU) of a video block within a current video frame orpicture relative to a predictive block within a reference picture.

A predictive block is a block that is found to closely match the PU ofthe video block to be coded in terms of pixel difference, which may bedetermined by sum of absolute difference (SAD), sum of square difference(SSD), or other difference metrics. In some examples, the encodingdevice 104 may calculate values for sub-integer pixel positions ofreference pictures stored in picture memory 64. For example, theencoding device 104 may interpolate values of one-quarter pixelpositions, one-eighth pixel positions, or other fractional pixelpositions of the reference picture. Therefore, motion estimation unit 42may perform a motion search relative to the full pixel positions andfractional pixel positions and output a motion vector with fractionalpixel precision.

Motion estimation unit 42 calculates a motion vector for a PU of a videoblock in an inter-coded slice by comparing the position of the PU to theposition of a predictive block of a reference picture. The referencepicture may be selected from a first reference picture list (List 0) ora second reference picture list (List 1), each of which identify one ormore reference pictures stored in picture memory 64. Motion estimationunit 42 sends the calculated motion vector to entropy encoding unit 56and motion compensation unit 44.

Motion compensation, performed by motion compensation unit 44, mayinvolve fetching or generating the predictive block based on the motionvector determined by motion estimation, possibly performinginterpolations to sub-pixel precision. Upon receiving the motion vectorfor the PU of the current video block, motion compensation unit 44 maylocate the predictive block to which the motion vector points in areference picture list. The encoding device 104 forms a residual videoblock by subtracting pixel values of the predictive block from the pixelvalues of the current video block being coded, forming pixel differencevalues. The pixel difference values form residual data for the block,and may include both luma and chroma difference components. Summer 50represents the component or components that perform this subtractionoperation. Motion compensation unit 44 may also generate syntax elementsassociated with the video blocks and the video slice for use by thedecoding device 112 in decoding the video blocks of the video slice.

Intra-prediction processing unit 46 may intra-predict a current block,as an alternative to the inter-prediction performed by motion estimationunit 42 and motion compensation unit 44, as described above. Inparticular, intra-prediction processing unit 46 may determine anintra-prediction mode to use to encode a current block. In someexamples, intra-prediction processing unit 46 may encode a current blockusing various intra-prediction modes, e.g., during separate encodingpasses, and intra-prediction processing unit 46 may select anappropriate intra-prediction mode to use from the tested modes. Forexample, intra-prediction processing unit 46 may calculaterate-distortion values using a rate-distortion analysis for the varioustested intra-prediction modes, and may select the intra-prediction modehaving the best rate-distortion characteristics among the tested modes.Rate-distortion analysis generally determines an amount of distortion(or error) between an encoded block and an original, unencoded blockthat was encoded to produce the encoded block, as well as a bit rate(that is, a number of bits) used to produce the encoded block.Intra-prediction processing unit 46 may calculate ratios from thedistortions and rates for the various encoded blocks to determine whichintra-prediction mode exhibits the best rate-distortion value for theblock.

In any case, after selecting an intra-prediction mode for a block,intra-prediction processing unit 46 may provide information indicativeof the selected intra-prediction mode for the block to entropy encodingunit 56. Entropy encoding unit 56 may encode the information indicatingthe selected intra-prediction mode. The encoding device 104 may includein the transmitted bitstream configuration data definitions of encodingcontexts for various blocks as well as indications of a most probableintra-prediction mode, an intra-prediction mode index table, and amodified intra-prediction mode index table to use for each of thecontexts. The bitstream configuration data may include a plurality ofintra-prediction mode index tables and a plurality of modifiedintra-prediction mode index tables (also referred to as codeword mappingtables).

After prediction processing unit 41 generates the predictive block forthe current video block via either inter-prediction or intra-prediction,the encoding device 104 forms a residual video block by subtracting thepredictive block from the current video block. The residual video datain the residual block may be included in one or more TUs and applied totransform processing unit 52. Transform processing unit 52 transformsthe residual video data into residual transform coefficients using atransform, such as a discrete cosine transform (DCT) or a conceptuallysimilar transform. Transform processing unit 52 may convert the residualvideo data from a pixel domain to a transform domain, such as afrequency domain.

Transform processing unit 52 may send the resulting transformcoefficients to quantization unit 54. Quantization unit 54 quantizes thetransform coefficients to further reduce bit rate. The quantizationprocess may reduce the bit depth associated with some or all of thecoefficients. The degree of quantization may be modified by adjusting aquantization parameter. In some examples, quantization unit 54 may thenperform a scan of the matrix including the quantized transformcoefficients. Alternatively, entropy encoding unit 56 may perform thescan.

Following quantization, entropy encoding unit 56 entropy encodes thequantized transform coefficients. For example, entropy encoding unit 56may perform context adaptive variable length coding (CAVLC), contextadaptive binary arithmetic coding (CABAC), syntax-based context-adaptivebinary arithmetic coding (SBAC), probability interval partitioningentropy (PIPE) coding or another entropy encoding technique. Followingthe entropy encoding by entropy encoding unit 56, the encoded bitstreammay be transmitted to the decoding device 112, or archived for latertransmission or retrieval by the decoding device 112. Entropy encodingunit 56 may also entropy encode the motion vectors and the other syntaxelements for the current video slice being coded.

Inverse quantization unit 58 and inverse transform processing unit 60apply inverse quantization and inverse transformation, respectively, toreconstruct the residual block in the pixel domain for later use as areference block of a reference picture. Motion compensation unit 44 maycalculate a reference block by adding the residual block to a predictiveblock of one of the reference pictures within a reference picture list.Motion compensation unit 44 may also apply one or more interpolationfilters to the reconstructed residual block to calculate sub-integerpixel values for use in motion estimation. Summer 62 adds thereconstructed residual block to the motion compensated prediction blockproduced by motion compensation unit 44 to produce a reference block forstorage in picture memory 64. The reference block may be used by motionestimation unit 42 and motion compensation unit 44 as a reference blockto inter-predict a block in a subsequent video frame or picture.

In this manner, the encoding device 104 of FIG. 6 represents an exampleof a video encoder configured to perform any of the techniques describedherein. In some cases, some of the techniques of this disclosure mayalso be implemented by post processing device 57.

FIG. 7 is a block diagram illustrating an example decoding device 112.The decoding device 112 includes an entropy decoding unit 80, predictionprocessing unit 81, inverse quantization unit 86, inverse transformprocessing unit 88, summer 90, filter unit 91, and picture memory 92.Prediction processing unit 81 includes motion compensation unit 82 andintra prediction processing unit 84. The decoding device 112 may, insome examples, perform a decoding pass generally reciprocal to theencoding pass described with respect to the encoding device 104 fromFIG. 6 .

During the decoding process, the decoding device 112 receives an encodedvideo bitstream that represents video blocks of an encoded video sliceand associated syntax elements sent by the encoding device 104. In someembodiments, the decoding device 112 may receive the encoded videobitstream from the encoding device 104. In some embodiments, thedecoding device 112 may receive the encoded video bitstream from anetwork entity 79, such as a server, a media-aware network element(MANE), a video editor/splicer, or other such device configured toimplement one or more of the techniques described above. Network entity79 may or may not include the encoding device 104. Some of thetechniques described in this disclosure may be implemented by networkentity 79 prior to network entity 79 transmitting the encoded videobitstream to the decoding device 112. In some video decoding systems,network entity 79 and the decoding device 112 may be parts of separatedevices, while in other instances, the functionality described withrespect to network entity 79 may be performed by the same device thatcomprises the decoding device 112.

The entropy decoding unit 80 of the decoding device 112 entropy decodesthe bitstream to generate quantized coefficients, motion vectors, andother syntax elements. Entropy decoding unit 80 forwards the motionvectors and other syntax elements to prediction processing unit 81. Thedecoding device 112 may receive the syntax elements at the video slicelevel and/or the video block level. Entropy decoding unit 80 may processand parse both fixed-length syntax elements and variable-length syntaxelements in or more parameter sets, such as a VPS, SPS, and PPS.

When the video slice is coded as an intra-coded (I) slice, intraprediction processing unit 84 of prediction processing unit 81 maygenerate prediction data for a video block of the current video slicebased on a signaled intra-prediction mode and data from previouslydecoded blocks of the current frame or picture. When the video frame iscoded as an inter-coded (i.e., B, P or GPB) slice, motion compensationunit 82 of prediction processing unit 81 produces predictive blocks fora video block of the current video slice based on the motion vectors andother syntax elements received from entropy decoding unit 80. Thepredictive blocks may be produced from one of the reference pictureswithin a reference picture list. The decoding device 112 may constructthe reference frame lists, List 0 and List 1, using default constructiontechniques based on reference pictures stored in picture memory 92.

Motion compensation unit 82 determines prediction information for avideo block of the current video slice by parsing the motion vectors andother syntax elements, and uses the prediction information to producethe predictive blocks for the current video block being decoded. Forexample, motion compensation unit 82 may use one or more syntax elementsin a parameter set to determine a prediction mode (e.g., intra- orinter-prediction) used to code the video blocks of the video slice, aninter-prediction slice type (e.g., B slice, P slice, or GPB slice),construction information for one or more reference picture lists for theslice, motion vectors for each inter-encoded video block of the slice,inter-prediction status for each inter-coded video block of the slice,and other information to decode the video blocks in the current videoslice.

Motion compensation unit 82 may also perform interpolation based oninterpolation filters. Motion compensation unit 82 may use interpolationfilters as used by the encoding device 104 during encoding of the videoblocks to calculate interpolated values for sub-integer pixels ofreference blocks. In this case, motion compensation unit 82 maydetermine the interpolation filters used by the encoding device 104 fromthe received syntax elements, and may use the interpolation filters toproduce predictive blocks.

Inverse quantization unit 86 inverse quantizes, or de-quantizes, thequantized transform coefficients provided in the bitstream and decodedby entropy decoding unit 80. The inverse quantization process mayinclude use of a quantization parameter calculated by the encodingdevice 104 for each video block in the video slice to determine a degreeof quantization and, likewise, a degree of inverse quantization thatshould be applied. Inverse transform processing unit 88 applies aninverse transform (e.g., an inverse DCT or other suitable inversetransform), an inverse integer transform, or a conceptually similarinverse transform process, to the transform coefficients in order toproduce residual blocks in the pixel domain.

After motion compensation unit 82 generates the predictive block for thecurrent video block based on the motion vectors and other syntaxelements, the decoding device 112 forms a decoded video block by summingthe residual blocks from inverse transform processing unit 88 with thecorresponding predictive blocks generated by motion compensation unit82. Summer 90 represents the component or components that perform thissummation operation. If desired, loop filters (either in the coding loopor after the coding loop) may also be used to smooth pixel transitions,or to otherwise improve the video quality. Filter unit 91 is intended torepresent one or more loop filters such as a deblocking filter, anadaptive loop filter (ALF), and a sample adaptive offset (SAO) filter.Although filter unit 91 is shown in FIG. 7 as being an in loop filter,in other configurations, filter unit 91 may be implemented as a postloop filter. The decoded video blocks in a given frame or picture arethen stored in picture memory 92, which stores reference pictures usedfor subsequent motion compensation. Picture memory 92 also storesdecoded video for later presentation on a display device, such as videodestination device 122 shown in FIG. 1 .

In this manner, the decoding device 112 of FIG. 7 represents an exampleof a video decoder configured to perform any of the techniques describedherein.

As used herein, the term “computer-readable medium” includes, but is notlimited to, portable or non-portable storage devices, optical storagedevices, and various other mediums capable of storing, containing, orcarrying instruction(s) and/or data. A computer-readable medium mayinclude a non-transitory medium in which data can be stored and thatdoes not include carrier waves and/or transitory electronic signalspropagating wirelessly or over wired connections. Examples of anon-transitory medium may include, but are not limited to, a magneticdisk or tape, optical storage media such as compact disk (CD) or digitalversatile disk (DVD), flash memory, memory or memory devices. Acomputer-readable medium may have stored thereon code and/ormachine-executable instructions that may represent a procedure, afunction, a subprogram, a program, a routine, a subroutine, a module, asoftware package, a class, or any combination of instructions, datastructures, or program statements. A code segment may be coupled toanother code segment or a hardware circuit by passing and/or receivinginformation, data, arguments, parameters, or memory contents.Information, arguments, parameters, data, etc. may be passed, forwarded,or transmitted via any suitable means including memory sharing, messagepassing, token passing, network transmission, or the like.

In some embodiments the computer-readable storage devices, mediums, andmemories can include a cable or wireless signal containing a bit streamand the like. However, when mentioned, non-transitory computer-readablestorage media expressly exclude media such as energy, carrier signals,electromagnetic waves, and signals per se.

Specific details are provided in the description above to provide athorough understanding of the embodiments and examples provided herein.However, it will be understood by one of ordinary skill in the art thatthe embodiments may be practiced without these specific details. Forclarity of explanation, in some instances the present technology may bepresented as including individual functional blocks including functionalblocks comprising devices, device components, steps or routines in amethod embodied in software, or combinations of hardware and software.Additional components may be used other than those shown in the figuresand/or described herein. For example, circuits, systems, networks,processes, and other components may be shown as components in blockdiagram form in order not to obscure the embodiments in unnecessarydetail. In other instances, well-known circuits, processes, algorithms,structures, and techniques may be shown without unnecessary detail inorder to avoid obscuring the embodiments.

Individual embodiments may be described above as a process or methodwhich is depicted as a flowchart, a flow diagram, a data flow diagram, astructure diagram, or a block diagram. Although a flowchart may describethe operations as a sequential process, many of the operations can beperformed in parallel or concurrently. In addition, the order of theoperations may be re-arranged. A process is terminated when itsoperations are completed, but could have additional steps not includedin a figure. A process may correspond to a method, a function, aprocedure, a subroutine, a subprogram, etc. When a process correspondsto a function, its termination can correspond to a return of thefunction to the calling function or the main function.

Processes and methods according to the above-described examples can beimplemented using computer-executable instructions that are stored orotherwise available from computer-readable media. Such instructions caninclude, for example, instructions and data which cause or otherwiseconfigure a general purpose computer, special purpose computer, or aprocessing device to perform a certain function or group of functions.Portions of computer resources used can be accessible over a network.The computer executable instructions may be, for example, binaries,intermediate format instructions such as assembly language, firmware,source code, etc. Examples of computer-readable media that may be usedto store instructions, information used, and/or information createdduring methods according to described examples include magnetic oroptical disks, flash memory, USB devices provided with non-volatilememory, networked storage devices, and so on.

Devices implementing processes and methods according to thesedisclosures can include hardware, software, firmware, middleware,microcode, hardware description languages, or any combination thereof,and can take any of a variety of form factors. When implemented insoftware, firmware, middleware, or microcode, the program code or codesegments to perform the necessary tasks (e.g., a computer-programproduct) may be stored in a computer-readable or machine-readablemedium. A processor(s) may perform the necessary tasks. Typical examplesof form factors include laptops, smart phones, mobile phones, tabletdevices or other small form factor personal computers, personal digitalassistants, rackmount devices, standalone devices, and so on.Functionality described herein also can be embodied in peripherals oradd-in cards. Such functionality can also be implemented on a circuitboard among different chips or different processes executing in a singledevice, by way of further example.

The instructions, media for conveying such instructions, computingresources for executing them, and other structures for supporting suchcomputing resources are example means for providing the functionsdescribed in the disclosure.

In the foregoing description, aspects of the application are describedwith reference to specific embodiments thereof, but those skilled in theart will recognize that the application is not limited thereto. Thus,while illustrative embodiments of the application have been described indetail herein, it is to be understood that the inventive concepts may beotherwise variously embodied and employed, and that the appended claimsare intended to be construed to include such variations, except aslimited by the prior art. Various features and aspects of theabove-described application may be used individually or jointly.Further, embodiments can be utilized in any number of environments andapplications beyond those described herein without departing from thebroader spirit and scope of the specification. The specification anddrawings are, accordingly, to be regarded as illustrative rather thanrestrictive. For the purposes of illustration, methods were described ina particular order. It should be appreciated that in alternateembodiments, the methods may be performed in a different order than thatdescribed.

One of ordinary skill will appreciate that the less than (“<”) andgreater than (“>”) symbols or terminology used herein can be replacedwith less than or equal to (“≤”) and greater than or equal to (“≥”)symbols, respectively, without departing from the scope of thisdescription.

Where components are described as being “configured to” perform certainoperations, such configuration can be accomplished, for example, bydesigning electronic circuits or other hardware to perform theoperation, by programming programmable electronic circuits (e.g.,microprocessors, or other suitable electronic circuits) to perform theoperation, or any combination thereof.

The phrase “coupled to” refers to any component that is physicallyconnected to another component either directly or indirectly, and/or anycomponent that is in communication with another component (e.g.,connected to the other component over a wired or wireless connection,and/or other suitable communication interface) either directly orindirectly.

Claim language or other language in the disclosure reciting “at leastone of” a set and/or “one or more” of a set indicates that one member ofthe set or multiple members of the set (in any combination) satisfy theclaim. For example, claim language reciting “at least one of A and B”means A, B, or A and B. In another example, claim language reciting “atleast one of A, B, and C” means A, B, C, or A and B, or A and C, or Band C, or A and B and C. The language “at least one of” a set and/or“one or more” of a set does not limit the set to the items listed in theset. For example, claim language reciting “at least one of A and B” canmean A, B, or A and B, and can additionally include items not listed inthe set of A and B.

The various illustrative logical blocks, modules, circuits, andalgorithm steps described in connection with the embodiments disclosedherein may be implemented as electronic hardware, computer software,firmware, or combinations thereof. To clearly illustrate thisinterchangeability of hardware and software, various illustrativecomponents, blocks, modules, circuits, and steps have been describedabove generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. Skilled artisans may implement the described functionality invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the present application.

The techniques described herein may also be implemented in electronichardware, computer software, firmware, or any combination thereof. Suchtechniques may be implemented in any of a variety of devices such asgeneral purposes computers, wireless communication device handsets, orintegrated circuit devices having multiple uses including application inwireless communication device handsets and other devices. Any featuresdescribed as modules or components may be implemented together in anintegrated logic device or separately as discrete but interoperablelogic devices. If implemented in software, the techniques may berealized at least in part by a computer-readable data storage mediumcomprising program code including instructions that, when executed,performs one or more of the methods described above. Thecomputer-readable data storage medium may form part of a computerprogram product, which may include packaging materials. Thecomputer-readable medium may comprise memory or data storage media, suchas random access memory (RAM) such as synchronous dynamic random accessmemory (SDRAM), read-only memory (ROM), non-volatile random accessmemory (NVRAM), electrically erasable programmable read-only memory(EEPROM), FLASH memory, magnetic or optical data storage media, and thelike. The techniques additionally, or alternatively, may be realized atleast in part by a computer-readable communication medium that carriesor communicates program code in the form of instructions or datastructures and that can be accessed, read, and/or executed by acomputer, such as propagated signals or waves.

The program code may be executed by a processor, which may include oneor more processors, such as one or more digital signal processors(DSPs), general purpose microprocessors, an application specificintegrated circuits (ASICs), field programmable logic arrays (FPGAs), orother equivalent integrated or discrete logic circuitry. Such aprocessor may be configured to perform any of the techniques describedin this disclosure. A general purpose processor may be a microprocessor;but in the alternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration. Accordingly, the term “processor,” as used herein mayrefer to any of the foregoing structure, any combination of theforegoing structure, or any other structure or apparatus suitable forimplementation of the techniques described herein. In addition, in someaspects, the functionality described herein may be provided withindedicated software modules or hardware modules configured for encodingand decoding, or incorporated in a combined video encoder-decoder(CODEC).

Illustrative aspects of the disclosure include:

Aspect 1: An apparatus for processing video data, comprising: at leastone memory; and at least one processor coupled to the at least onememory, the at least one processor being configured to: obtain apicture; and determine at least one of a width and a height of a filmgrain synthesis block of the picture based on at least one of a widthand a height of the picture.

Aspect 2: The apparatus of Aspect 1, wherein a height value for the filmgrain synthesis block shall be in the range of 1 to 8, inclusive.

Aspect 3: The apparatus of any one of Aspects 1 or 2, wherein a widthvalue for the film grain synthesis block shall be in the range of 8 toW, inclusive, where W is a maximum width of a corresponding grainpattern.

Aspect 4: The apparatus of any one of Aspects 1 to 3, wherein, todetermine at least one of the width and the height of the film grainsynthesis block of the picture based on at least one of the width andthe height of the picture, the at least one processor is configured to:determine the width and the height of the film grain synthesis block ofthe picture based the width and the height of the picture.

Aspect 5: The apparatus of any one of Aspects 1 to 4, wherein the atleast one processor is configured to: determine a width of the filmgrain synthesis block is equal to a width of a corresponding grainpattern; and set a horizontal offset used to select a block of the grainpattern to 0.

Aspect 6: The apparatus of any one of Aspects 1 to 5, wherein theapparatus includes a decoder.

Aspect 7: The apparatus of any one of Aspects 1 to 5, wherein theapparatus includes an encoder.

Aspect 8: The apparatus of any one of Aspects 1 to 7, further comprisinga display configured to display one or more output pictures.

Aspect 9: The apparatus of any one of Aspects 1 to 8, further comprisinga camera configured to capture one or more pictures.

Aspect 10: The apparatus of any one of Aspects 1 to 9, wherein theapparatus is a mobile device.

Aspect 11: A method of processing video data, comprising operationsaccording to Aspects 1 to 10.

Aspect 12: A non-transitory computer-readable medium having storedthereon instructions that, when executed by one or more processors,cause the one or more processors to perform operations according toAspects 1 to 10.

Aspect 13: An apparatus for processing video data, comprising one ormore means for performing operations according to Aspects 1 to 10.

Aspect 14: An apparatus for processing video data, comprising: memory;and one or more processors coupled to the memory, the one or moreprocessors being configured to: obtain video data including at least onepicture; and generate, based on the video data, a plurality of grainpatterns, each grain pattern of the plurality of grain patternsincluding one vertical cut-off frequency and one horizontal cut-offfrequency.

Aspect 15: The apparatus of Aspect 14, wherein each grain pattern of theplurality of grain patterns includes a grain pattern size of 32×32.

Aspect 16: The apparatus of any one of Aspects 14 or 15, wherein the onehorizontal cut-off frequency is from a first set of seven availablehorizontal cut-off frequencies and wherein the one vertical cur-offfrequency is from a second set of seven available vertical cut-offfrequencies.

Aspect 17: The apparatus of any one of Aspects 14 to 16, wherein the atleast one processor is configured to: determine, for a grain pattern ofthe plurality of grain patterns, at least one cut-off frequency variableat least in part by adding a value of 4 to an available cut-offfrequency from the seven available cut-off frequencies.

Aspect 18: The apparatus of Aspect 17, wherein, to determine at leastone of the one vertical cut-off frequency or the one horizontal cut-offfrequency for the grain pattern, the at least one processor isconfigured to: determine, for the grain pattern, a horizontal cut-offfrequency variable at least in part by adding the value of 4 to theavailable cut-off frequency from the seven available cut-offfrequencies; and determine, for the grain pattern, a vertical cut-offfrequency variable at least in part by adding the value of 4 to theavailable cut-off frequency from the seven available cut-offfrequencies.

Aspect 19: The apparatus of any one of Aspects 14 to 18, wherein theapparatus includes a decoder.

Aspect 20: The apparatus of any one of Aspects 14 to 18, wherein theapparatus includes an encoder.

Aspect 21: The apparatus of any one of Aspects 14 to 20, furthercomprising a display configured to display one or more output pictures.

Aspect 22: The apparatus of any one of Aspects 14 to 21, furthercomprising a camera configured to capture one or more pictures.

Aspect 23: The apparatus of any one of Aspects 14 to 22, wherein theapparatus is a mobile device.

Aspect 24: A method of processing video data, comprising operationsaccording to Aspects 14 to 23.

Aspect 25: A non-transitory computer-readable medium having storedthereon instructions that, when executed by one or more processors,cause the one or more processors to perform operations according toAspects 14 to 23.

Aspect 26: An apparatus for processing video data, comprising one ormore means for performing operations according to Aspects 14 to 23.

Aspect 27: An apparatus for processing video data, comprising: memory;and one or more processors coupled to the memory, the one or moreprocessors being configured to: obtain video data including at least onepicture; generate, based on the video data, a plurality of grainpatterns, each grain pattern of the plurality of grain patterns includesa grain pattern size of 32×32.

Aspect 28: The apparatus of Aspect 27, wherein each grain pattern of theplurality of grain patterns includes one vertical cut-off frequency andone horizontal cut-off frequency.

Aspect 29: The apparatus of Aspect 28, wherein the one horizontalcut-off frequency is from a first set of seven available horizontalcut-off frequencies and wherein the one vertical cut-off frequency isfrom a second set of seven available vertical cut-off frequencies.

Aspect 30: The apparatus of any one of Aspects 28 or 29, wherein the atleast one processor is configured to: determine, for a grain pattern ofthe plurality of grain patterns, at least one cut-off frequency variableat least in part by adding a value of 4 to an available cut-offfrequency from the seven available cut-off frequencies.

Aspect 31: The apparatus of Aspect 30, wherein, to determine at leastone of the one vertical cut-off frequency or the one horizontal cur-offfrequency for the grain pattern, the at least one processor isconfigured to: determine, for the grain pattern, a horizontal cut-offfrequency variable at least in part by adding the value of 4 to theavailable cut-off frequency from the seven available cut-offfrequencies; and determine, for the grain pattern, a vertical cut-offfrequency variable at least in part by adding the value of 4 to theavailable cut-off frequency from the seven available cut-offfrequencies.

Aspect 32: The apparatus of any one of Aspects 27 to 31, wherein theapparatus includes a decoder.

Aspect 33: The apparatus of any one of Aspects 27 to 31, wherein theapparatus includes an encoder.

Aspect 34: The apparatus of any one of Aspects 27 to 33, furthercomprising a display configured to display one or more output pictures.

Aspect 35: The apparatus of any one of Aspects 27 to 34, furthercomprising a camera configured to capture one or more pictures.

Aspect 36: The apparatus of any one of Aspects 27 to 35, wherein theapparatus is a mobile device.

Aspect 37: A method of processing video data, comprising operationsaccording to Aspects 27 to 36.

Aspect 38: A non-transitory computer-readable medium having storedthereon instructions that, when executed by one or more processors,cause the one or more processors to perform operations according toAspects 27 to 36.

Aspect 39: An apparatus for processing video data, comprising one ormore means for performing operations according to Aspects 27 to 36.

Aspect 40: An apparatus for processing video data, comprising: memory;and one or more processors coupled to the memory, the one or moreprocessors being configured to: obtain video data including at least onepicture; determine a value for a film grain application syntax element,the value of the film grain application syntax element specifyingwhether at least one film grain characteristic (FGC) message is presentin a bitstream and whether film grain synthesis is to be applied toencoded video data of the bitstream; and generate, based on the videodata, the bitstream including the encoded video data and the film grainapplication syntax element.

Aspect 41: The apparatus of Aspect 40, wherein the value for the filmgrain application syntax element includes a first value, the first valuespecifying that the at least one FGC message is present in the bitstreamand that film grain synthesis is to be applied to the encoded video dataof the bitstream.

Aspect 42: The apparatus of Aspect 40, wherein the value for the filmgrain application syntax element includes a second value, the secondvalue specifying that the at least one FGC message may be present in thebitstream and that film grain synthesis may be applied to the encodedvideo data of the bitstream.

Aspect 43: The apparatus of any one of Aspects 40 to 42, wherein thefilm grain application syntax element is included in an extension fieldof a sequence parameter set (SPS) of the bitstream.

Aspect 44: The apparatus of any one of Aspects 40 to 42, wherein thefilm grain application syntax element is included in a video usabilityinformation (VUI) payload extension field of the bitstream.

Aspect 45: The apparatus of any one of Aspects 40 to 44, wherein theapparatus includes an encoder.

Aspect 46: A method of processing video data, comprising operationsaccording to Aspects 40 to 45.

Aspect 47: A non-transitory computer-readable medium having storedthereon instructions that, when executed by one or more processors,cause the one or more processors to perform operations according toAspects 40 to 45.

Aspect 48: An apparatus for processing video data, comprising one ormore means for performing operations according to Aspects 40 to 45.

Aspect 49: An apparatus for processing video data, comprising: memory;and one or more processors coupled to the memory, the one or moreprocessors being configured to: obtain a bitstream including encodedvideo data; determine, from the bitstream, a value for a film grainapplication syntax element, the value of the film grain applicationsyntax element specifying whether at least one film grain characteristic(FGC) message is present in the bitstream and whether film grainsynthesis is to be applied to the encoded video data of the bitstream;and process the encoded video data based on the value of the film grainapplication syntax element.

Aspect 50: The apparatus of Aspect 49, wherein the value for the filmgrain application syntax element includes a first value, the first valuespecifying that the at least one FGC message is present in the bitstreamand that film grain synthesis is to be applied to the encoded video dataof the bitstream.

Aspect 51: The apparatus of Aspect 49, wherein the value for the filmgrain application syntax element includes a second value, the secondvalue specifying that the at least one FGC message may be present in thebitstream and that film grain synthesis may be applied to the encodedvideo data of the bitstream.

Aspect 52: The apparatus of any one of Aspects 49 to 51, wherein thefilm grain application syntax element is included in an extension fieldof a sequence parameter set (SPS) of the bitstream.

Aspect 53: The apparatus of any one of Aspects 49 to 51, wherein thefilm grain application syntax element is included in a video usabilityinformation (VUI) payload extension field of the bitstream.

Aspect 54: The apparatus of any one of Aspects 49 to 53, wherein theapparatus includes a decoder.

Aspect 55: A method of processing video data, comprising operationsaccording to Aspects 49 to 54.

Aspect 56: A non-transitory computer-readable medium having storedthereon instructions that, when executed by one or more processors,cause the one or more processors to perform operations according toAspects 49 to 54.

Aspect 57: An apparatus for processing video data, comprising one ormore means for performing operations according to Aspects 49 to 54.

Aspect 58: An apparatus for processing video data, comprising: memory;and one or more processors coupled to the memory, the one or moreprocessors being configured to: obtain video data including at least onepicture; determine a value for a film grain constraint syntax element,the value of the film grain constraint syntax element specifying whetherat least one film grain characteristic message including film grainmetadata is present in a bitstream; and generate, based on the videodata, the bitstream including the encoded video data and the film grainconstraint syntax element.

Aspect 59: The apparatus of Aspect 58, wherein the value for the filmgrain constraint syntax element includes a first value, the first valuespecifying that at least one film grain characteristic message is notpresent in a bitstream.

Aspect 60: The apparatus of Aspect 58, wherein the value for the filmgrain constraint syntax element includes a second value, the secondvalue specifying that at least one film grain characteristic message maybe present in a bitstream.

Aspect 61: The apparatus of Aspect 58, wherein the value for the filmgrain constraint syntax element includes a second value, the secondvalue specifying that at least one film grain characteristic message ispresent in a bitstream.

Aspect 62: The apparatus of any one of Aspects 58 to 61, wherein the atleast one film grain characteristic message is a film graincharacteristics supplemental enhancement information (SEI) message.

Aspect 63: The apparatus of any one of Aspects 58 to 61, wherein the atleast one film grain characteristic message is a user data registered byRecommendation ITU-T T.35 supplemental enhancement information (SEI)message.

Aspect 64: The apparatus of any one of Aspects 58 to 63, wherein thefilm grain application syntax element is included in a video usabilityinformation (VUI) parameters field of the bitstream.

Aspect 65: The apparatus of any one of Aspects 58 to 63, wherein thefilm grain application syntax element is included in a generalconstraints information syntax of the bitstream.

Aspect 66: The apparatus of any one of Aspects 58 to 65, wherein theapparatus includes an encoder.

Aspect 67: A method of processing video data, comprising operationsaccording to Aspects 58 to 65.

Aspect 68: A non-transitory computer-readable medium having storedthereon instructions that, when executed by one or more processors,cause the one or more processors to perform operations according toAspects 58 to 65.

Aspect 69: An apparatus for processing video data, comprising one ormore means for performing operations according to Aspects 58 to 65.

Aspect 70: An apparatus for processing video data, comprising: memory;and one or more processors coupled to the memory, the one or moreprocessors being configured to: obtain a bitstream including encodedvideo data; determine, from the bitstream, a value for a film grainconstraint syntax element, the value of the film grain constraint syntaxelement specifying whether at least one film grain characteristicmessage including film grain metadata is present in a bitstream; processthe encoded video data based on the value of the film grain constraintsyntax element.

Aspect 71: The apparatus of Aspect 70, wherein the value for the filmgrain constraint syntax element includes a first value, the first valuespecifying that at least one film grain characteristic message is notpresent in a bitstream.

Aspect 72: The apparatus of Aspect 70, wherein the value for the filmgrain constraint syntax element includes a second value, the secondvalue specifying that at least one film grain characteristic message maybe present in a bitstream.

Aspect 73: The apparatus of Aspect 70, wherein the value for the filmgrain constraint syntax element includes a second value, the secondvalue specifying that at least one film grain characteristic message ispresent in a bitstream.

Aspect 74: The apparatus of any one of Aspects 70 to 73, wherein the atleast one film grain characteristic message is a film graincharacteristics supplemental enhancement information (SEI) message.

Aspect 75: The apparatus of any one of Aspects 70 to 73, wherein the atleast one film grain characteristic message is a user data registered byRecommendation ITU-T T.35 supplemental enhancement information (SEI)message.

Aspect 76: The apparatus of any one of Aspects 70 to 75, wherein thefilm grain application syntax element is included in a video usabilityinformation (VUI) parameters field of the bitstream.

Aspect 77: The apparatus of any one of Aspects 70 to 75, wherein thefilm grain application syntax element is included in a generalconstraints information syntax of the bitstream.

Aspect 78: The apparatus of any one of Aspects 70 to 77, wherein theapparatus includes a decoder.

Aspect 79: A method of processing video data, comprising operationsaccording to Aspects 70 to 77.

Aspect 80: A non-transitory computer-readable medium having storedthereon instructions that, when executed by one or more processors,cause the one or more processors to perform operations according toAspects 70 to 77.

Aspect 81: An apparatus for processing video data, comprising one ormore means for performing operations according to Aspects 70 to 77.

Aspect 82: An apparatus for processing video data, comprising: memory;and one or more processors coupled to the memory, the one or moreprocessors being configured to perform operations according to Aspects 1to 10, Aspects 14 to 23, Aspects 27 to 36, Aspects 40 to 45, Aspects 49to 54, Aspects 58 to 66, Aspects 70 to 78, or any combination thereof.

Aspect 83: A method of processing video data, comprising operationsaccording to Aspects 1 to 10, Aspects 14 to 23, Aspects 27 to 36,Aspects 40 to 45, Aspects 49 to 54, Aspects 58 to 66, Aspects 70 to 78,or any combination thereof.

Aspect 84: A non-transitory computer-readable medium having storedthereon instructions that, when executed by one or more processors,cause the one or more processors to perform operations according toAspects 1 to 10, Aspects 14 to 23, Aspects 27 to 36, Aspects 40 to 45,Aspects 49 to 54, Aspects 58 to 66, Aspects 70 to 78, or any combinationthereof.

Aspect 85: An apparatus for processing video data, comprising one ormore means for performing operations according to Aspects 1 to 10,Aspects 14 to 23, Aspects 27 to 36, Aspects 40 to 45, Aspects 49 to 54,Aspects 58 to 66, Aspects 70 to 78, or any combination thereof.

Aspect 86: An apparatus for processing video data, comprising: at leastone memory; and at least one processor coupled to the at least onememory, the at least one processor being configured to: obtain videodata including a picture; determine a width of a film grain synthesisblock of the picture based on at least one of a width and a height ofthe picture; determine a height of the film grain synthesis block of thepicture is one; determine a block size of the film grain synthesis blockbased on the determined width and height; and select a grain block basedon the determined block size.

Aspect 87: The apparatus of aspect 86, wherein a width value for thefilm grain synthesis block is in a range of 8 to W, inclusive, where Wis a maximum width of a corresponding grain pattern.

Aspect 88. The apparatus of aspect 86, wherein, to determine at leastone of the width and the height of the film grain synthesis block of thepicture based on at least one of the width and the height of thepicture, the at least one processor is configured to: determine thewidth of the film grain synthesis block of the picture based the widthand the height of the picture.

Aspect 89. The apparatus of aspect 86, wherein the at least oneprocessor is further configured to: obtain a current block of samplesfrom the picture; obtain a set of pixels from the current block ofsamples based on the determined block size; and determine an averageluma value for the set of pixels, and wherein to select the grain block,the at least one processor is further configured to select the grainblock based on the average luma value.

Aspect 90. The apparatus of aspect 89, wherein the set of pixelscomprises a line of pixels from the current block of samples, andwherein the at least one processor is configured to: determine theaverage luma value for each line of pixels for the current block ofsamples; determine an overall average luma value for the current blockof samples based on the average luma value for each line of pixels; anddetermine an intensity level based on the overall average luma value.

Aspect 91. The apparatus of aspect 90, wherein the at least oneprocessor is configured to: select a grain pattern based on theintensity level; and randomly select at least a vertical offset, whereinto select the grain block, the at least one processor is furtherconfigured to select the grain block from the grain pattern based on thevertical offset.

Aspect 92. The apparatus of aspect 91, wherein the at least oneprocessor is configured to: decode the current block of samples; add theselected grain block to the decoded current block of samples to generatean output current block; and output the output current block.

Aspect 93. The apparatus of aspect 86, wherein the at least oneprocessor is configured to: determine a width of the film grainsynthesis block is equal to a width of a corresponding grain pattern;and set a horizontal offset used to select a block of the grain patternto 0.

Aspect 94. The apparatus of aspect 86, wherein the apparatus includes adecoder.

Aspect 95. The apparatus of aspect 86, wherein the apparatus includes anencoder.

Aspect 96. The apparatus of aspect 86, further comprising a displayconfigured to display one or more output pictures.

Aspect 97. The apparatus of aspect 86, further comprising a cameraconfigured to capture one or more pictures.

Aspect 98. The apparatus of aspect 86, wherein the apparatus is a mobiledevice.

Aspect 99. A method for processing video data, the method comprising:obtaining video data including a picture; determining a width of a filmgrain synthesis block of the picture based on at least one of a widthand a height of the picture; determining a height of the film grainsynthesis block of the picture is one; determining a block size of thefilm grain synthesis block based on the determined width and height; andselecting a grain block based on the determined block size.

Aspect 100. The method of aspect 99, wherein a width value for the filmgrain synthesis block is in a range of 8 to W, inclusive, where W is amaximum width of a corresponding grain pattern.

Aspect 101. The method of aspect 99, wherein determining at least one ofthe width and the height of the film grain synthesis block of thepicture based on at least one of the width and the height of the picturecomprises determining the width of the film grain synthesis block of thepicture based the width and the height of the picture.

Aspect 102. The method of aspect 99, further comprising: obtaining acurrent block of samples from the picture; obtaining a set of pixelsfrom the current block of samples based on the determined block size;and determining an average luma value for the set of pixels, whereinselecting the grain block comprises selecting the grain block based onthe average luma value.

Aspect 103. The method of aspect 102, wherein the set of pixelscomprises a line of pixels from the current block of samples, andwherein the method further comprises: determining the average luma valuefor each line of pixels for the current block of samples; determining anoverall average luma value for the current block of samples based on theaverage luma value for each line of pixels; and determining an intensitylevel based on the overall average luma value.

Aspect 104. The method of aspect 103, further comprising: selecting agrain pattern based on the intensity level; and randomly selecting atleast a vertical offset, wherein selecting the grain block comprisesselecting the grain block from the grain pattern based on the verticaloffset.

Aspect 105. The method of aspect 104, further comprising: decoding thecurrent block of samples; adding the selected grain block to the decodedcurrent block of samples to generate an output current block; andoutputting the output current block.

Aspect 106. The method of aspect 99, further comprising: determining awidth of the film grain synthesis block is equal to a width of acorresponding grain pattern; and setting a horizontal offset used toselect a block of the grain pattern to 0.

Aspect 107. A non-transitory computer-readable medium having storedthereon instructions that, when executed by at least one or moreprocessors, cause the at least one or more processors to: obtain videodata including a picture; determine a width of a film grain synthesisblock of the picture based on at least one of a width and a height ofthe picture; determine a height of the film grain synthesis block of thepicture is one; determine a block size of the film grain synthesis blockbased on the determined width and height; and select a grain block basedon the determined block size.

Aspect 108. The non-transitory computer-readable medium of aspect 107,wherein a width value for the film grain synthesis block is in a rangeof 8 to W, inclusive, where W is a maximum width of a correspondinggrain pattern.

Aspect 109. The non-transitory computer-readable medium of aspect 107,wherein, to determine at least one of the width and the height of thefilm grain synthesis block of the picture based on at least one of thewidth and the height of the picture, the instructions cause the at leastone processor to: determine the width of the film grain synthesis blockof the picture based the width and the height of the picture.

Aspect 110. The non-transitory computer-readable medium of aspect 107,wherein instruction further cause the at least one processor to: obtaina current block of samples from the picture; obtain a set of pixels fromthe current block of samples based on the determined block size; anddetermine an average luma value for the set of pixels, and wherein toselect the grain block, the instructions cause the at least oneprocessor to select the grain block based on the average luma value.

Aspect 111. The non-transitory computer-readable medium of aspect 110,wherein the set of pixels comprises a line of pixels from the currentblock of samples, and wherein the instruction further cause the at leastone processor to: determine the average luma value for each line ofpixels for the current block of samples; determine an overall averageluma value for the current block of samples based on the average lumavalue for each line of pixels; and determine an intensity level based onthe overall average luma value.

Aspect 112. The non-transitory computer-readable medium of aspect 111,wherein the instructions further cause the at least one processor to:select a grain pattern based on the intensity level; and randomly selectat least a vertical offset, wherein to select the grain block, theinstructions cause the at least one processor to select the grain blockfrom the grain pattern based on the vertical offset.

Aspect 113. The non-transitory computer-readable medium of aspect 112,wherein the instructions further cause the at least one processor to:decode the current block of samples; add the selected grain block to thedecoded current block of samples to generate an output current block;and output the output current block.

Aspect 114. The non-transitory computer-readable medium of aspect 107,wherein the instructions further cause the at least one processor to:determine a width of the film grain synthesis block is equal to a widthof a corresponding grain pattern; and set a horizontal offset used toselect a block of the grain pattern to 0.

Aspect 115: An apparatus for processing video data, comprising one ormore means for performing operations according to Aspects 86 to 98,Aspects 99 to 106, Aspects 107 to 114, or any combination thereof

What is claimed is:
 1. An apparatus for processing video data,comprising: at least one memory; and at least one processor coupled tothe at least one memory, the at least one processor being configured to:obtain video data including a picture; determine a width of a film grainsynthesis block of the picture based on at least one of a width and aheight of the picture; determine a height of the film grain synthesisblock of the picture is one; determine a block size of the film grainsynthesis block based on the determined width and height; and select agrain block based on the determined block size.
 2. The apparatus ofclaim 1, wherein a width value for the film grain synthesis block is ina range of 8 to W, inclusive, where W is a maximum width of acorresponding grain pattern.
 3. The apparatus of claim 1, wherein, todetermine at least one of the width and the height of the film grainsynthesis block of the picture based on at least one of the width andthe height of the picture, the at least one processor is configured to:determine the width of the film grain synthesis block of the picturebased the width and the height of the picture.
 4. The apparatus of claim1, wherein the at least one processor is further configured to: obtain acurrent block of samples from the picture; obtain a set of pixels fromthe current block of samples based on the determined block size; anddetermine an average luma value for the set of pixels, and wherein toselect the grain block, the at least one processor is further configuredto select the grain block based on the average luma value.
 5. Theapparatus of claim 4, wherein the set of pixels comprises a line ofpixels from the current block of samples, and wherein the at least oneprocessor is configured to: determine the average luma value for eachline of pixels for the current block of samples; determine an overallaverage luma value for the current block of samples based on the averageluma value for each line of pixels; and determine an intensity levelbased on the overall average luma value.
 6. The apparatus of claim 5,wherein the at least one processor is configured to: select a grainpattern based on the intensity level; and randomly select at least avertical offset, wherein to select the grain block, the at least oneprocessor is further configured to select the grain block from the grainpattern based on the vertical offset.
 7. The apparatus of claim 6,wherein the at least one processor comprises a video decoder and isconfigured to: decode the current block of samples; add the selectedgrain block to the decoded current block of samples to generate anoutput current block; and output the output current block.
 8. Theapparatus of claim 7, further comprising a display configured to displayone or more pictures that include the current block.
 9. The apparatus ofclaim 1, wherein the at least one processor is configured to: determinea width of the film grain synthesis block is equal to a width of acorresponding grain pattern; and set a horizontal offset used to selecta block of the grain pattern to
 0. 10. The apparatus of claim 1, whereinthe apparatus includes an encoder.
 11. The apparatus of claim 1, furthercomprising a camera configured to capture one or more pictures.
 12. Amethod for processing video data, the method comprising: obtaining videodata including a picture; determining a width of a film grain synthesisblock of the picture based on at least one of a width and a height ofthe picture; determining a height of the film grain synthesis block ofthe picture is one; determining a block size of the film grain synthesisblock based on the determined width and height; and selecting a grainblock based on the determined block size.
 13. The method of claim 12,wherein a width value for the film grain synthesis block is in a rangeof 8 to W, inclusive, where W is a maximum width of a correspondinggrain pattern.
 14. The method of claim 12, wherein determining at leastone of the width and the height of the film grain synthesis block of thepicture based on at least one of the width and the height of the picturecomprises determining the width of the film grain synthesis block of thepicture based the width and the height of the picture.
 15. The method ofclaim 12, further comprising: obtaining a current block of samples fromthe picture; obtaining a set of pixels from the current block of samplesbased on the determined block size; and determining an average lumavalue for the set of pixels, wherein selecting the grain block comprisesselecting the grain block based on the average luma value.
 16. Themethod of claim 15, wherein the set of pixels comprises a line of pixelsfrom the current block of samples, and wherein the method furthercomprises: determining the average luma value for each line of pixelsfor the current block of samples; determining an overall average lumavalue for the current block of samples based on the average luma valuefor each line of pixels; and determining an intensity level based on theoverall average luma value.
 17. The method of claim 16, furthercomprising: selecting a grain pattern based on the intensity level; andrandomly selecting at least a vertical offset, wherein selecting thegrain block comprises selecting the grain block from the grain patternbased on the vertical offset.
 18. The method of claim 17, furthercomprising: decoding the current block of samples; adding the selectedgrain block to the decoded current block of samples to generate anoutput current block; and outputting the output current block.
 19. Themethod of claim 12, further comprising: determining a width of the filmgrain synthesis block is equal to a width of a corresponding grainpattern; and setting a horizontal offset used to select a block of thegrain pattern to
 0. 20. A non-transitory computer-readable medium havingstored thereon instructions that, when executed by at least one or moreprocessors, cause the at least one or more processors to: obtain videodata including a picture; determine a width of a film grain synthesisblock of the picture based on at least one of a width and a height ofthe picture; determine a height of the film grain synthesis block of thepicture is one; determine a block size of the film grain synthesis blockbased on the determined width and height; and select a grain block basedon the determined block size.